leeshuwei.leo@gmail.com

Why Print-Ready Files Matter

Custom envelope printing is a precision process: the artwork is printed on flat sheets, then folded, gummed and cut into envelopes. If the artwork is built to the wrong spec, every envelope in the run carries the error. A single misplaced bleed, a missing 3 mm, or a 72 DPI logo doesn’t just look bad — it fails prepress QA and costs a production cycle.

This guide is the exact checklist our factory’s prepress team applies to every custom envelope printing order. Build your files to these standards and they pass on the first pass.

The Core Numbers (Memorize These)

Spec	Value
Bleed	3 mm (⅛ in) on all sides
Safe margin	6 mm (¼ in) inside the trim edge
Resolution	300 DPI at final size
Color mode	CMYK (spot colors as PMS)
File format	PDF/X-1a or PDF/X-4
Fonts	Outlined / embedded
Max ink coverage	300% (avoid over-saturation)

Bleed: What It Is and How to Set It

Bleed is the area of artwork that extends past the final trim line. When the printed sheet is die-cut into envelopes, mechanical tolerance means the cut can shift ±1 mm — without bleed, white edges appear on full-bleed designs.

Set your document to the envelope flat size plus 3 mm on every side
Extend background colors, images and full-bleed panels into the bleed zone
Keep everything that must not be cut (text, logos, address blocks) 6 mm inside the trim line

Safe Margins: Protecting Critical Elements

The safe margin is the no-go zone for anything important. For envelopes, three zones deserve special care:

General safe margin — 6 mm from all trim edges
Address zone — keep the delivery-address area (lower-right third of the front) free of graphics; postal sorting machines must read it
Flap areas — the front and back flaps fold and gum; artwork within 10 mm of the flap edge can distort at the crease

Resolution and File Formats

Element	Requirement
Photos and raster art	300 DPI at final print size
Logos	Vector preferred (AI, EPS, PDF); raster at ≥ 600 DPI
Text	Vector text, outlined or embedded
File	PDF/X-1a (flattened, fonts embedded)
Color	CMYK; RGB files are converted (colors shift!)

Color Management

CMYK build — specify coated or uncoated target; envelope paper is uncoated in most cases
Spot colors — reference PMS numbers (e.g., PMS 293 C); we match to the physical fan deck
Proofing — soft proofs are indicative only; hard proofs available for critical brand colors
White ink — required for bright colors on kraft or translucent envelopes; designate the white plate separately

Envelope-Specific Layout Rules

Element	Position
Return address	Top-left of front (US) or back flap (EU)
Delivery address	Lower-right third of front (window envelopes: see window placement)
Postage	Top-right corner — keep 15 × 15 mm clear
Barcode	Lower-right corner, 12 mm from bottom edge (leave clean)
Flap print	Back flap printable area ends 12 mm before the flap fold

The Preflight Checklist (Run Before Sending)

[ ] Document size = flat envelope size + 3 mm bleed each side
[ ] All critical elements inside 6 mm safe margin
[ ] Images ≥ 300 DPI; logos vector or 600+ DPI
[ ] CMYK color mode; PMS noted for spot colors
[ ] PDF/X-1a exported; fonts outlined
[ ] Address/postage/barcode zones clear of graphics
[ ] Max ink coverage ≤ 300%
[ ] Window designs: address block positioned per window die (see window standards)

Common Rejections (What Fails Prepress)

Issue	Consequence
No bleed on full-bleed design	White edges on finished envelopes
72 DPI logo	Blurry brand — rejected or re-ripped
RGB colors	Visible shift after CMYK conversion
Fonts not embedded	Missing glyphs in final output
Artwork in address zone	Postal non-compliance
Text inside safe margin	Clipped by die tolerance

FAQ

What is the standard bleed for envelope printing?
3 mm (⅛ in) on all sides of the flat envelope size. Full-bleed designs must extend into this zone.

What file format should I send for envelope printing?
PDF/X-1a with fonts outlined and colors in CMYK. Vector logos preferred; raster images at 300 DPI minimum.

What resolution is needed for envelope artwork?
300 DPI at final size for photos and raster art; logos as vectors or 600+ DPI rasters.

Do you provide envelope printing templates?
Yes — on custom envelope printing we provide die-line templates (with bleed and safe margins pre-set) for every standard and custom size.

What happens if my file fails prepress?
We flag the issue with a corrected proof request before production — no silent rework, no surprise charges. Files that need fixing are quoted transparently.

Related Guides

What Are Durable Envelopes?

Durable envelopes are heavy-duty mailing envelopes made from materials that resist tearing, puncturing, moisture and rough handling — Tyvek (high-density polyethylene fiber) being the best known, alongside heavy-weight kraft and laminated papers. They protect documents through courier networks, international shipping, and field operations.

For a custom envelope manufacturer, the durable category requires different production standards than paper envelopes: printing needs special inks, sealing needs matched adhesives, and cutting needs sharp, heat-controlled tooling to avoid fiber melt.

Material Comparison: Tyvek vs Tear-Resistant Paper

Property	Tyvek	Heavy Kraft	Laminated Paper
Tear resistance	★★★★★	★★★	★★★★
Water resistance	★★★★★ (waterproof)	★★	★★★★
Weight	Very light	Heavy	Medium
Print quality	Good (special inks)	Good	Excellent
Cost	High	Low	Medium
Common use	International docs, samples	Standard heavy mail	Premium protective mail

Tyvek Grades Used in Envelopes

Grade	Weight	Use
Tyvek 1025D	54 gsm	Standard mailing envelopes
Tyvek 1056D	66 gsm	Heavy-duty, larger sizes
Tyvek 1073B	78 gsm	Maximum durability, industrial

Manufacturer’s note: Tyvek is specified by DuPont grade, not gsm alone. Grades differ in fiber density and surface smoothness, which directly affects printability and seal adhesion. Always confirm the grade with your supplier.

Production Standards for Tyvek Envelopes

Cutting — die-cutting with sharp, cooled tooling; blunt or hot dies melt the fiber edges instead of cutting them
Sealing — Tyvek requires aggressive adhesives; standard paper gum won’t bond. Use hot-melt or pressure-sensitive adhesive matched to the grade
Printing — water-based inks can soak the fiber; use UV or solvent-based inks with corona treatment
Folding — Tyvek doesn’t crease like paper; design with “living hinge” folds and allow natural stiffness
Perforations — tear strips must be laser-perforated for clean, straight tearing

Tear-Resistant Paper Standards

For buyers who want durability without the Tyvek cost:

Spec	Value
Base paper	120–160 gsm long-fiber kraft
Reinforcement	1–2 plies or fiber-laminated construction
Tear test	Elmendorf ≥ 1,800 mN (machine direction)
Water resistance	Water-repellent coating (Cobb ≤ 25 g/m²)
Print	Standard offset/CMYK works without special inks

Sizes and Formats

Size	Dimensions (in)	Use
#10	4⅛ × 9½	Legal documents, international mail
6 × 9	6 × 9	Certificates, small samples
9 × 12	9 × 12	Contracts, passports, media kits
10 × 13	10 × 13	Large documents, product samples
Custom	Any	Custom durable envelopes

Specialty Formats

Expandable (gusseted) — side or bottom gussets for thicker contents
Reclosable — zipper or flap closures for reusable field envelopes
Document pouches — sealed Tyvek pouches with tamper-evident closure

Quality Control Checklist

Tear test — Elmendorf per batch; fiber melt check on cut edges (no fused edges)
Seal integrity — peel test after 24 h aging; no delamination on Tyvek
Print adhesion — tape-pull test on printed surfaces (no ink lift)
Water test — contents remain dry after 1 h water exposure (Tyvek grade)
Sampling — AQL 2.5 general inspection

Common Durable Envelope Mistakes

Using paper-gum adhesive on Tyvek — seals fail in transit
Water-based inks on untreated Tyvek — smudged, unreadable branding
Blunt dies on fiber materials — frayed, weak edges that tear at the flap
Choosing Tyvek when tear-resistant paper is enough — paying premium for unnecessary specs

FAQ

What are durable envelopes made of?
Most commonly Tyvek (spun-bonded polyethylene fiber) or heavy long-fiber kraft with water-repellent coating. Both resist tearing and rough handling beyond standard paper envelopes.

Are Tyvek envelopes waterproof?
Yes — Tyvek is water-resistant and protects contents from rain and splashes. Fully waterproof seals require heat-seal or specialty closures, not standard gum.

Can you print logos on durable envelopes?
Yes — Tyvek uses UV/solvent inks with corona treatment; tear-resistant paper prints like standard stock. See custom durable envelopes.

What’s the difference between Tyvek and paper envelopes?
Tyvek is roughly 3× more tear-resistant, waterproof, and lighter — at 3–5× the material cost. Paper wins when durability needs are moderate.

Do durable envelopes cost more?
Material cost is the main driver: Tyvek 3–5× standard paper, tear-resistant kraft ~1.5–2×. Volume pricing applies — request a quote for exact numbers.

Related Guides

What Are Corporate Envelope Size Standards?

Corporate envelope size refers to the standard dimensions used for business mail — dominated by the #10 envelope (4⅛ × 9½ in) for letters, supported by #9 reply envelopes, 6×9 and 9×12 flats for documents. When a company orders stationery, the envelope set is built around these standards so letterhead, inserts and reply cards all match.

Business letterhead envelopes are the branded versions: the same standard sizes, printed with the company logo, return address and colors to match the letterhead. For corporate identity, size consistency is a quiet but critical detail — a mismatched envelope set undermines an otherwise polished brand.

Corporate Envelope Size Chart

Envelope	Dimensions (in)	mm	Use in the Corporate Set
#10	4⅛ × 9½	105 × 241	Main letter envelope
#9	3⅞ × 8⅞	98 × 225	Reply envelope (fits inside #10)
6 × 9	6 × 9	152 × 229	Unfolded documents
9 × 12	9 × 12	229 × 305	Reports, contracts, media kits
#6¾	3⅝ × 6½	92 × 165	Small notes, cards
A2	4⅜ × 5¾	111 × 146	Invitations, thank-you cards

Matching Letterhead Standards

Item	Standard Size
US Letter paper	8½ × 11 in
Corporate letterhead	8½ × 11 in
Business card	3½ × 2 in
#10 envelope fits	Letter folded in thirds

Corporate Envelope Design Standards

Brand consistency — logo position and size should match the letterhead layout (same corner placement, same scale relationship)
Return address — top-left corner on the front, or centered on the back flap (European convention); pick one and stay consistent
Color matching — use the corporate Pantone colors; spot-color printing guarantees exact matching
Typographic scale — envelope design is small-format: body text below 8 pt will reproduce poorly in print
Window variant — statement mailings use #10 window envelopes so the address prints only on the letter; the window style should still carry the brand frame

Printing Options for Corporate Envelopes

Option	Best For
1–2 color spot (PMS)	Classic corporate look, lowest cost at volume
Full-color CMYK	Photography, gradient branding
Foil stamping	Executive suites, luxury positioning
Embossing	Tactile logo mark, premium stationery
Security tint	Payroll and HR correspondence

Consistency tip: Print letterhead and envelopes in the same production run when possible — paper shade and ink density stay identical across the set.

Quality Control for Corporate Runs

Color matching — ΔE ≤ 2.0 against the approved corporate proof
Registration — ≤ 0.1 mm for multi-color logos
Dimensions — ±1.6 mm; a #10 that varies looks wrong in a letter tray
Fiber direction — with the length; corporate envelopes must fold crisply
Sampling — AQL 2.5 general inspection

Common Corporate Envelope Mistakes

Different logo size on envelope vs. letterhead — the most visible inconsistency
Using full CMYK when the brand is 2 PMS colors — higher cost, worse match
Printing the return address in the wrong corner for the destination market
Overlooking the reply envelope — #9 must match the set (it goes inside the #10)

FAQ

What is the standard corporate envelope size?
The #10 envelope (4⅛ × 9½ in) is the standard for corporate letters. Reply envelopes are #9 (3⅞ × 8⅞ in); flats for documents are 6×9 and 9×12.

What are business letterhead envelopes?
Standard-size envelopes printed with a company’s logo, return address and brand colors, matching the letterhead. They’re the branded layer of corporate stationery.

Should my envelope match my letterhead exactly?
Yes — same logo placement logic, same colors (spot-color matched), and ideally produced in the same run to lock paper shade.

Can I order a full corporate stationery set from one factory?
Yes — letterhead, envelopes, business cards and reply cards can be produced together. See business envelopes with logo or request a quote.

What size envelope do I need for an 8½ × 11 letter?
A #10 envelope (4⅛ × 9½ in) fits a US Letter folded in thirds. For unfolded documents, use a 9×12 envelope.

Related Guides

What Is a 9×12 Envelope?

A 9×12 envelope is the standard large flat envelope for documents that should not be folded — reports, brochures, contracts, magazines, artwork, and media kits. At 9 × 12 inches (229 × 305 mm), it fits letter-size documents unfolded, plus a few sheets of card stock or a small catalog.

For print resellers and corporate procurement teams, custom 9×12 envelopes are among the highest-volume “flat” products: they’re ordered in bulk, printed with branding, and must meet strict postal size rules.

9×12 Envelope Size Standards

Spec	Value
Standard size	9 × 12 in (229 × 305 mm)
Common variants	9½ × 12½ in · 10 × 13 in · 12 × 15.5 in
Standard paper	24 lb bond (89 gsm)
Heavy paper	28 lb (105 gsm) — recommended for mailing card stock
Closure	Remoistenable gum or self-seal (peel & seal)
Opening style	Side-opening (standard) or top-opening

Size Variant Chart

Size (in)	mm	Common Use
9 × 12	229 × 305	Standard reports, brochures
9½ × 12½	241 × 318	Documents + card stock
10 × 13	254 × 330	Catalogs, magazines
12 × 15½	305 × 394	Oversized media kits
Custom	Any	Custom 9×12 envelopes

Manufacturer’s note: The opening style matters for automated insertion. Side-opening 9×12 envelopes are the default; top-opening is used for manual stuffing or specific inserting machines. Specify your inserting method and we’ll match the machine.

Paper Specs for 9×12 Envelopes

Weight	gsm	Behavior
20 lb bond	74	Light, economical — fine for internal mail
24 lb bond	89	Standard; balanced weight and feel
28 lb bond	105	Recommended for heavy contents, premium feel
32 lb bond	120	Rigid, premium; watch postal weight limits

Fiber direction — must run with the long dimension for clean, crack-free folds
Opacity — 24 lb white wove has ~92% opacity; upgrade to 28 lb or security tint if contents must stay hidden
Recycled/FSC options — available at all standard weights

Postal Compliance (USPS “Large Envelope” Class)

9×12 envelopes qualify as USPS Large Envelope (Flats) — which affects pricing and design:

Requirement	Spec
Min size	11½ in length, 6⅛ in height
Max size	15 in length, 12 in height, ¾ in thickness
Address position	Delivery address in the center of the long dimension, within the address zone
Barcode	Intelligent Mail barcode required for automation rates
Rigid/rectangular	Must be flexible enough to pass automated equipment

Compliance tip: Flats priced as “flat-shaped” mail must be uniformly thick and flexible. Contents with card stock up to 1/4 in are fine; anything thicker should ship as a parcel.

Printing Standards for 9×12 Envelopes

Print area — full front panel available; back flap for return address or legal text
Bleed — 3 mm all sides
Safe margin — 6 mm; keep the address zone and barcode area clear
Full-color CMYK — standard for catalogs and branded mailings
Spot color — cost-effective for simple logos at high volume
File specs — 300 DPI, PDF/X-1a, outlined fonts — see our print-ready file standards

Quality Control Checklist

Dimensions — ±1.6 mm on length/width
Fold crease — no cracking at 90° bend, fiber direction verified
Gumming — uniform adhesive lane, no gaps > 0.5 mm
Print registration — ≤ 0.1 mm
Sampling — AQL 2.5 general inspection

Common 9×12 Envelope Mistakes

Ordering 9×12 for contents that are 9 × 12 themselves — documents need clearance; order 9½ × 12½
Ignoring thickness limits — overstuffed flats get reclassified as parcels (higher postage)
Artwork covering the address zone — breaks automation eligibility
Paper too light for card stock contents — contents show through, envelope looks cheap

FAQ

What is the standard 9×12 envelope size?
9 × 12 in (229 × 305 mm), typically 24 lb bond paper with side opening. Custom sizes from 9½ × 12½ to 12 × 15½ are common.

Can I mail an 8½ × 11 document unfolded in a 9×12 envelope?
Yes — that’s exactly what it’s for. Add ¼–½ in clearance when contents include card stock.

Do 9×12 envelopes cost more to mail?
They mail as USPS Large Envelope (Flats) — cheaper than parcels but more than letter mail. Automation-compliant design (barcode, address zone) keeps rates lowest.

Can I get custom printed 9×12 envelopes?
Yes — full-color printing, custom sizes, and bulk quantities. See custom 9×12 envelopes or request a quote.

What paper weight should I use?
24 lb for standard documents; 28 lb when mailing card stock or when the envelope carries heavy branding. For large white envelopes with a premium feel, 28–32 lb is the sweet spot.

Related Guides

What Are Bubble Envelopes?

Bubble envelopes (bubble mailers) are protective mailing envelopes lined with air-filled polyethylene bubbles. They protect fragile items — electronics, jewelry, cosmetics, books with dust jackets — during shipping, combining the convenience of an envelope with the cushioning of a box.

Bulk bubble envelopes are a staple of e-commerce operations, print-on-demand sellers and 3PL warehouses. Because they’re ordered in volume, production standards around bubble quality, seal strength and consistent sizing matter enormously.

Bubble Envelope Size Chart

Size	Dimensions (in)	Fits (typical)
#000	6 × 10	Small accessories, phone cases
#00	7¼ × 10½	Jewelry, small electronics
#0	8½ × 12	Tablets, small books
#1	10⅜ × 15⅝	Books, apparel (folded)
#2	12 × 17	Larger books, boxes of samples
#3	13 × 18½	Bigger parcels, multiple items
#4	14½ × 19½	Oversized items
Custom	Any	Custom bubble mailers

Manufacturer’s note: Sizing conventions vary by supplier. Always spec the *internal* dimensions — bubble lining reduces usable space by 10–15 mm on each side.

Cushioning Standards (Bubble Quality)

Spec	Standard	Premium
Bubble diameter	10 mm	10 mm
Bubble height	3–4 mm	4–5 mm
Film thickness	50–60 μm	70–90 μm
Burst rate (sampling)	≤ 1%	≤ 0.5%

Air retention — bubbles must hold ≥ 95% of initial air volume after 30 days
Burst testing — ASTM D1596 drop test: contents protected at 1 m drop (standard), 2 m (premium)
Consistency — bubble pattern must be uniform across the lining; no flat spots

Outer Shell Standards

Layer	Material	Thickness
Outer layer	Kraft paper or white paper	80–100 gsm
Bubble lining	LDPE film	50–90 μm
Optional rigid insert	Cardboard	400+ gsm

Kraft vs. White Bubble Mailers

	Kraft	White
Look	Natural, economical	Clean, premium
Print	1–2 spot colors best	Full CMYK, white-ink options
Cost	Lower	Higher
Common use	E-commerce default	Branded retail, electronics

Seal Strength Standards

Bubble mailers use two seal types:

Peel-and-seal (self-seal) — the default for e-commerce; the release liner peels cleanly and the adhesive bonds instantly
Heat-seal — permanent closure for high-security or tamper-evident shipments

Seal Test Requirements

Adhesion strength ≥ 4.5 N/25mm (peel test)
No residue transfer — liner removal must not leave adhesive residue on hands or contents
Cold test — seal integrity at 0 °C (winter shipping); adhesive must not stiffen and fail
Heat test — no adhesive bleed-through at 50 °C storage

Printing Standards for Bubble Envelopes

Method	Best For
1–2 color flexo/spot	Return addresses, simple logos — lowest cost
Full-color flexo	Branded designs on white mailers
Custom size + print	Retail-ready packaging

Print area — front face only; the back face carries the mailing address panel (leave it clear)
Barcode zone — keep the lower-right quadrant free of graphics for shipping labels
Ink adhesion — rub test on film and paper surfaces; flexo inks on film need corona treatment

Quality Control Checklist

Bubble burst rate — ≤ 1% in batch sampling
Dimensions — ±3 mm on length/width (stacking and auto-dispensing tolerance)
Seal strength — peel test per roll/batch
Print registration — ≤ 0.5 mm
Appearance — no wrinkles, creases or glue stains on the outer face

Common Bubble Mailer Mistakes

Ordering by outer size without accounting for bubble lining — contents don’t fit
Full-bleed print too close to the seal edge — adhesive picks up ink, weakens the seal
No cold-weather seal test — seals fail in winter shipping lanes
Assuming all “bulk” suppliers test bubbles — request burst-rate data

FAQ

What sizes do bubble envelopes come in?
From #000 (6 × 10 in) to #4 (14½ × 19½ in) plus custom sizes. The most popular for e-commerce are #0–#2.

How much protection do bubble mailers provide?
Standard construction protects against 1 m drops and normal handling; premium film and bubbles handle 2 m drops. For heavier items, use boxes.

Can I get custom printed bubble mailers?
Yes — logo, full-color branding, and custom sizes are available. Bulk pricing applies from a few thousand units. See bulk bubble envelopes or request a quote.

Are bubble mailers recyclable?
Kraft bubble mailers are curbside recyclable in many regions (paper shell + bubble liner separated); white mailers less so. Recycled-content options are available.

What’s the difference between bubble and padded envelopes?
“Padded” is the general category (any cushioning); “bubble” specifically means air-bubble lining. Other padded types use foam or fiber fill — lighter, less protective, and cheaper.

Related Guides

What Is a Security Envelope?

A security envelope is an envelope with an interior pattern printed inside the envelope paper, so document contents can’t be read against the light. The pattern — dots, waves, or solid color — hides checks, payroll details, medical records and legal documents during transit.

Custom security envelopes add another layer: tamper-evident sealing, where the adhesive or pattern visibly breaks if someone opens the envelope and reseals it. For banks, payroll providers, clinics and law firms, these two features are non-negotiable.

Interior Tint Standards

Tint Type	Pattern	Opacity	Best For
Wave pattern	Scalloped waves	40–60%	Checks, statements
Dot matrix	Fine dots	50–70%	Payroll, confidential documents
Solid tint	Full color inside	80–95%	Maximum privacy
Branded tint	Custom pattern with logo	Varies	Branded confidential mail
Double tint	Two-layer print	90%+	High-security mail

Manufacturer’s note: Tint opacity is measured by how much text is readable through the envelope at reading distance. Standard wave tint blocks casual reading; solid tint blocks held-against-light reading. For true protection against deliberate inspection, combine solid tint with tamper-evident seals.

Tamper-Evident Standards

Seal Type	How It Works	Use Case
Security adhesive	Adhesive releases fiber from the paper when peeled	Documents that must not be opened
Patterned adhesive	Seal breaks into a visible pattern on opening	Audit trails (the pattern shows “opened”)
Tear-resistant + adhesive	Combines strength with seal integrity	High-value mailing

Production Requirements for Tamper-Evident Seals

Adhesive fiber bond — the seal must pull paper fibers, not release cleanly (fiber-tear test per batch)
No re-sealability — a resealed envelope must be visibly different from an unopened one
Uniform application — no gaps wider than 0.5 mm in the adhesive lane
Moisture resistance — seal performance must hold at 40–90% relative humidity (standard test range)

Security Envelope Sizes

Envelope	Dimensions (in)	Common Use
#10 security	4⅛ × 9½	Payroll, statements, checks
#9 security	3⅞ × 8⅞	Reply envelopes for secure mail
6 × 9 security	6 × 9	Medical records, contracts
9 × 12 security	9 × 12	Legal documents, lab reports
Custom	Any	Per compliance requirement

Printing Standards for Security Envelopes

Front print — full CMYK, spot colors, foil stamping available (banks often use foil for security graphics)
Tint print layer — printed inside, before folding; must not bleed through to the front
Anti-scan features — for check mailers, patterned tints that interfere with document scanners are available
File standards — same prepress rules as any print job: 300 DPI, CMYK, PDF/X-1a print-ready files

Compliance and Testing

Test	Standard
Fiber tear	≥ 90% fiber transfer on peel test
Tint opacity	No text readable at 30 cm with standard interior lighting
Humidity	Seal integrity at 90% RH, 24 h
Automated sorting	Passes USPS automation clearance (no jamming, no window interference)

Common Security Envelope Mistakes

Using wave tint for truly sensitive mail — upgrade to solid tint
No fiber-tear test — a clean-peeling “security” seal is just a regular seal
Tint printed so dark it bleeds through to the front panel
Forgetting that window security envelopes exist — contents visible through the window are protected by design, not by tint

FAQ

What is a security tint envelope?
An envelope with a pattern printed on the inside of the paper that prevents document contents from being read against the light.

Are security envelopes tamper-proof?
No envelope is fully tamper-proof, but tamper-evident security envelopes show clear signs of opening — fiber-tear adhesive or breakable seal patterns. That deterrence is the standard for payroll and legal mail.

Can I print my logo on security envelopes?
Yes — full-color front printing with logo, plus branded interior tints for maximum brand presence. See custom security envelopes.

What security envelope size do I need for checks?
#10 (4⅛ × 9½ in) is the standard for checks and payroll. Some banks prefer #9 for reply envelopes.

Do security envelopes cost much more?
The interior tint adds a small per-unit cost; tamper-evident adhesive slightly more. Volume pricing applies — request a quote for exact numbers.

Related Guides

What Are Kraft Envelopes?

Kraft envelopes are made from kraft paper — a strong, unbleached or lightly bleached paper with a distinctive brown tone. They are the default choice for packaging, e-commerce shipping, document mailings and any business that wants an eco-friendly, natural look.

Kraft paper’s long-fiber composition makes it noticeably stronger than white wove paper at the same weight, which is why kraft envelopes dominate shipping and mailing applications. For a custom envelope manufacturer, kraft is also one of the most print-friendly sustainable materials — if handled with the right standards.

Kraft Paper Weight Standards

Kraft Weight	gsm	Typical Use
Light kraft	70–80 gsm	Light documents, invoices, interoffice mail
Standard kraft	90–120 gsm	General mailing, e-commerce packaging
Heavy kraft	140–200 gsm	Shipping documents, catalogs, rigid mailers
Kraft board	250+ gsm	Mailers requiring stiffness (boxes-style)

Manufacturer’s note: For most mailing applications we recommend 100–120 gsm kraft — strong enough to survive automated sorting without feeling board-like. Weights above 200 gsm generally require special folding equipment and are produced on a custom basis.

Kraft Paper Types and Grades

Grade	Characteristics
Natural (unbleached) kraft	Classic brown, highest strength, most eco-friendly
White-top kraft	White print surface on brown body — best of both worlds
Recycled kraft	Post-consumer fiber, variable shade (can be mottled)
Coated kraft	Smooth surface for premium printing; slightly less natural feel
FSC-certified kraft	Chain-of-custody certified sustainable sourcing

Printability: What You Need to Know

Kraft is absorbent and brown — three production rules apply:

Print colors shift — CMYK prints darker and warmer on brown kraft; convert artwork to spot colors when exact brand color matters
White ink is essential — for logos and bright graphics on natural kraft, white ink under-print is the industry standard
Higher absorbency — ink drying time is longer; presses run slightly slower, which is a minor cost factor on large runs

Standard Kraft Envelope Sizes

Size	Dimensions (in)	Common Use
#10	4⅛ × 9½	Documents, invoices
6 × 9	6 × 9	Catalogs, brochures
9 × 12	9 × 12	Reports, media kits, shipping documents
10 × 13	10 × 13	Large shipping, binders
12 × 15.5	12 × 15.5	Oversized shipping
Custom	Any	Custom sizes die-cut to spec

Strength and Sealing Standards

Basis weight vs. burst strength — kraft at 100 gsm delivers roughly 30–40% higher burst strength than white wove at the same weight
Sealing — kraft accepts both remoistenable gum and self-seal adhesive; self-seal is preferred for e-commerce (no licking, no moisture risk)
Tear resistance — natural kraft’s long fibers resist edge tears; reinforced edges available for heavy contents

Finishing Options

Finish	Application
Plain (no print)	Packaging, shipping — lowest cost
1–2 color spot print	Logos, return addresses — cost-effective brand
White ink + spot/CMYK	Full branding on natural kraft
Foil stamping	Premium retail packaging envelopes
Window	Kraft window envelopes for statements
Security tint	Kraft with interior pattern print

Quality Control Checklist

Fiber direction — must run with the envelope length for clean folds (no cracking)
Fold quality — no fiber lift or crack at the flap crease (90° bend test)
Gumming — uniform adhesive, no bleed-through on kraft’s darker surface
Color consistency — natural kraft shade varies between batches; we lock a shade sample before production
Sampling — AQL 2.5 general inspection

Common Kraft Envelope Mistakes

Designing CMYK artwork without white under-print — colors look muddy
Assuming all “recycled” kraft is the same shade — it isn’t; approve a physical sample
Using heavy board for standard mailing — postage and automated sorting issues
Ignoring fiber direction — envelopes crack along the fold when wrong

FAQ

What is kraft envelope paper?
Kraft paper is a strong, long-fiber paper made from wood pulp (usually unbleached), giving envelopes their signature brown color and high tear resistance.

Can you print full color on kraft envelopes?
Yes, with white ink under-print for bright colors. For exact brand colors, spot-color printing is recommended.

Are kraft envelopes eco-friendly?
Natural and recycled kraft envelopes are biodegradable, recyclable, and available FSC-certified — among the most sustainable envelope options.

What weight kraft should I use for shipping documents?
100–120 gsm handles most document shipping; use 140+ gsm for heavy or rigid contents.

Do you make custom size kraft envelopes?
Yes — any size, any quantity, with custom printing. See our kraft envelope manufacturing page or request a quote.

Related Guides

What Are Invitation Envelopes?

Invitation envelopes are the decorative envelopes used for weddings, events, corporate functions and personal stationery. Unlike business envelopes, they prioritize aesthetics — heavier paper, elegant finishes, and sizes matched to the card they carry.

For a custom envelope manufacturer, invitation envelopes are produced in standard series (A-series and Baronial) plus custom sizes. Because they are often printed in small-to-medium runs with premium finishes, they are a favorite product line for print resellers and event companies.

Invitation Envelope Size Chart

Envelope Style	Dimensions (in)	Dimensions (mm)	Card It Fits
A2	4⅜ × 5¾	111 × 146	4¼ × 5½ card (RSVP, save-the-date)
A6	4¾ × 6½	121 × 165	4½ × 6¼ card (flat invitation)
A7	5¼ × 7¼	133 × 184	5 × 7 card (standard invitation)
A8	5½ × 8⅛	140 × 206	5¼ × 7¾ card (announcements)
A9	5¾ × 8¾	146 × 222	5½ × 8½ card (large announcements)
A10	6 × 9½	152 × 241	5¾ × 9¼ card (presentations)
Baronial	4⅞ × 6⅞	124 × 175	4⅝ × 6¼ card (formal invites)
Square	5½ × 5½	140 × 140	Square cards (modern events)

Manufacturer’s note: The A-series (A2–A10) is the North American standard for invitations. “A” sizes are sized so the card fits with a ⅛ in margin on each side. Baronial envelopes feature a distinctive pointed flap and are the classic choice for formal wedding invitations.

Paper and Material Standards

Invitation envelopes are almost always heavier than business envelopes:

Material	Weight	Best For
Text weight (cardstock)	80–100 lb text	Standard invitations, RSVP cards
Cover stock	65–80 lb cover	Premium invitations, pocket folders
Laid / felt finish	80 lb text	Textured, luxurious feel
Kraft / recycled	70–90 lb	Rustic, eco-friendly weddings
Translucent (vellum)	60–80 lb	Modern layered designs

Finish Options

Metallic ink / foil stamping — gold, silver, rose gold for luxury
Embossing / debossing — monograms and crests
Thermography — raised, glossy lettering (traditional wedding look)
Peel-and-seal closure — preferred by event pros over moistening gum

Design Standards for Invitation Envelopes

Bleed: 3 mm on all sides for full-bleed prints
Safe margin: 6 mm minimum; the return address and postage sit inside this zone
Flap design: the pointed Baronial flap and the square flap each change the printable back area — plan artwork for the flap shape you choose
Envelope liner: a decorative liner inside the envelope is a popular upgrade; it must be glued cleanly without bubbling at the flap
Resolution & format: 300 DPI, CMYK, PDF/X-1a — same prepress standards as any print-ready file

Printing Options

Option	Note
Full-color CMYK	Photos, watercolor designs, gradients
Spot color (PMS)	Exact brand or wedding color matching
Foil stamping	Metallic accents on names, monograms
White ink	For kraft and translucent envelopes
Digital short-run	Cost-effective for 100–5,000 pcs
Offset long-run	Lowest per-unit cost above ~10,000 pcs

Quality Control Checklist

Die-cut accuracy — clean corners, no paper tear at flap points (±1 mm)
Foil/finish adhesion — no flaking after 90° bend test
Gumming — self-seal liner fully covers adhesive, no exposed glue
Color — ΔE ≤ 2.0 against approved proof
Sampling — AQL 2.5 general inspection

Common Invitation Envelope Mistakes

Ordering A6 for a 5 × 7 card (it won’t fit — use A7)
Full-bleed artwork without bleed margin, showing white edges
Metallic foil designed over textured paper — foil doesn’t bond well on rough surfaces
Ignoring the flap shape in the back-print design

FAQ

What is the standard invitation envelope size?
The most common is A7 (5¼ × 7¼ in), which fits a standard 5 × 7 invitation card. A2 (4⅜ × 5¾ in) is standard for RSVP cards.

What is a Baronial envelope?
A Baronial envelope (4⅞ × 6⅞ in) has a pointed, diagonal flap and is the traditional choice for formal wedding invitations.

Can I print on both sides of an invitation envelope?
Yes — front panel for branding, back flap for return address or monograms. Plan around the flap shape.

What paper weight should invitation envelopes be?
80 lb text or 65–80 lb cover. Heavier paper feels premium but adds postage weight and can crack at the fold if too stiff.

Do you offer small quantities for wedding invitations?
Yes, digital short-run printing starts at 100 pieces. For larger events and resellers, request a quote for per-unit pricing.

Related Guides

What Is a Window Envelope?

A window envelope is an envelope with a transparent panel cut into the front, letting the address printed on the letter inside show through — no need to print the address on the envelope itself. It is the standard for invoices, statements, payroll and direct mail, where thousands of letters are stuffed and mailed automatically.

Custom window envelopes give businesses full control over the window size, position, and the envelope’s print design. The most common format is the single-window #10 window envelope; double-window versions are used for mailings that show both a return address and a delivery address.

Window Envelope Sizes: Standard Dimensions

Envelope Style	Dimensions (in)	Window Position (typical)
#10 single window	4⅛ × 9½	⅞ in from left, ¾ in from bottom
#10 double window	4⅛ × 9½	Return window upper-left, address window lower
#9 single window	3⅞ × 8⅞	Same proportional position as #10
6 × 9 single window	6 × 9	Left side, mid-height
9 × 12 single window	9 × 12	Left side, mid-height
Custom window	Any size	Per artwork

Manufacturer’s note: Window sizes commonly range from 1⅛ × 3 in to 1¼ × 4 in. Custom window sizes and positions are die-cut, so anything within the printable area is possible — but standard positions cost less and run faster.

Window Position Rules (Postal & Print)

The window must line up with the address block on the letter inside. Two standards govern position:

USPS automation requirements — the delivery address must sit within the address zone of the envelope; the window must not obstruct the barcode clear zone
Print registration — the window is die-cut after printing, so a consistent die position (±1 mm) is what guarantees the address shows through fully

Standard #10 Window Position (mm from bottom-left of envelope)

Edge	Distance
Window left edge → envelope left edge	26 mm (1 in)
Window bottom edge → envelope bottom edge	19 mm (¾ in)
Minimum window size	25 × 76 mm
Maximum window size	32 × 102 mm

Design Rules for Window Envelope Artwork

Address block position: the address on the insert must sit inside the window area with at least 3 mm clearance on all sides
Safe margin: keep all other graphics 6 mm from the window edge — die-cut tolerance can shave into artwork that touches it
Window film: standard window film is clear 30–40 micron PET; anti-static and opaque-window variants are available for sensitive mail
Flap direction: specify whether the flap is on the back (standard) — this affects which side the window appears from

Printing Options for Custom Window Envelopes

Option	Detail
Full-color CMYK front	Branding around the window, common for billing and marketing mail
Security tint interior	Hides document content around the window area
Two-sided printing	Print on both front and back flap
Foil stamping	Premium window envelopes for luxury mailings

Common Window Envelope Design Mistakes

Address block misaligned with the window — the most common error; always test-stuff a proof
Graphics touching the window edge, clipped by die-cut tolerance
Using a matte film when barcode scanning is required (glare can cause non-reads)
Forgetting the return address window on double-window designs

FAQ

What is the standard window envelope size?
The most common is the #10 window envelope at 4⅛ × 9½ in, with a single window positioned ⅞ in from the left and ¾ in from the bottom.

Can I get custom window envelopes with my logo?
Yes — custom window envelopes can be printed full color with your logo and branding around any window size or position.

What is a double window envelope?
A double window envelope has two transparent panels: one for the return address and one for the delivery address, used for automated statement mailings.

Do window envelopes cost more than plain envelopes?
The window die-cut and film add a small per-unit cost, but automated addressing eliminates label and printing costs — for high-volume mailings, window envelopes are usually cheaper overall.

Can the window be on the left or right?
Yes. Standard is left; right-position windows are available for markets like the UK where addresses are positioned differently. Request a quote with your layout and we’ll confirm the die.

Related Guides

What Is a #10 Envelope?

The #10 envelope is the standard business envelope used for correspondence, invoices, checks, and direct mail across North America. At 4⅛ × 9½ inches (105 × 241 mm), it is the largest of the “regular” business sizes — the one that fits a standard US letter (8½ × 11 inches) folded into thirds.

When buyers search for #10 envelopes or number 10 envelopes, they are almost always looking for this exact workhorse of office mail. For a custom envelope manufacturer, it is also the most-produced format in the industry, which is why per-unit costs stay low and quality control is mature.

#10 Envelope Size Chart: Exact Dimensions

Specification	US Standard	Metric
Flat size (unsealed)	4⅛ × 9½ in	105 × 241 mm
Sealed size	4⅛ × 9½ in	105 × 241 mm
Standard paper weight	24 lb bond	89 gsm
Common alternative	20 lb bond	74 gsm
Fits	US Letter folded in thirds	A4 folded in thirds (slightly snug)

How #10 Compares to Other Business Envelope Sizes

Envelope Style	Dimensions (in)	Dimensions (mm)	Common Use
#9	3⅞ × 8⅞	98 × 225	Reply envelopes, bills
#10	4⅛ × 9½	105 × 241	Invoices, checks, direct mail
6 × 9	6 × 9	152 × 229	Unfolded documents, catalogs
9 × 12	9 × 12	229 × 305	Reports, brochures, media kits

Manufacturer’s note: Tolerances on all standard sizes are ±1.6 mm (±1/16 in). If your artwork is built to the exact nominal size, it will fit — but always respect the safe-margin guidelines below.

Paper Weight and Material Standards

The “standard” #10 envelope is printed on 24 lb bond (89 gsm) — heavy enough to feel professional, light enough to stay within postal weight limits. Lighter 20 lb stock is common for bulk mailers who optimize for postage; heavier 28–32 lb adds a premium feel for branded stationery.

What We Offer on #10 Envelopes

Material	Characteristics	Best For
White wove (24 lb)	Standard office feel, excellent print surface	Invoices, general correspondence
Premium smooth (28–32 lb)	Heavier, crisp, ideal for CMYK + spot colors	Branded stationery, proposals
Kraft / recycled	Eco-friendly, natural brown tone	Sustainability-conscious brands
Security tint (inside print)	Patterned interior, hides document contents	Payroll, medical, legal mail
Tyvek / tear-resistant	Water- and tear-resistant	Shipping documents, durable mail

Print Design Standards: Bleed, Safe Margins and File Formats

Getting production-ready artwork right the first time saves a full production cycle. These are the standards our prepress team checks on every custom #10 envelope order:

Bleed: 3 mm (⅛ in) on all sides — artwork that touches the edge must extend past the trim line
Safe margin: 6 mm (¼ in) inside the trim edge on all sides; critical text and logos must stay inside this zone
Address zone: leave the lower-left and lower-right quarters of the front free of graphics — automated sorting machines read the address area, and postal barcodes need clean space
Resolution: 300 DPI at final size; vector logos preferred (PDF, AI, EPS)
File format: PDF/X-1a or PDF/X-4, CMYK color mode, fonts outlined
Window alignment: if your design uses a window (#10 window envelopes), the address block must be positioned to show through the window at exactly 10 mm from the left edge of the envelope

Need the full prepress checklist? See our custom envelope print-ready file standards guide.

Printing and Finishing Options for Custom #10 Envelopes

A standard #10 envelope can carry far more than a return address. From a production standpoint, the print area is divided into:

Front panel — full-bleed capable; the main canvas for branding
Front flap — usually left blank or a single accent color; curl from the gummed flap can affect registration
Back flap — common spot for return address, legal disclaimers, or pattern prints (security tint)

Available Processes

Process	Use Case	Notes
Spot color (PMS)	Logos with brand colors	Most cost-effective for 1–2 colors
CMYK full color	Photos, gradients, complex artwork	Requires 24 lb or heavier stock
Foil stamping	Premium logos, metallic accents	Gold, silver, holographic
Embossing / debossing	Tactile branding	Adds a premium unboxing feel
Security tint	Confidential documents	Printed inside the envelope

Closure Types and Production Standards

Closure	Application	Notes
Remoistenable gum	Traditional, low cost	Standard moisture-activated adhesive
Self-seal (peel & seal)	Convenience, high volume	Release liner over pressure-sensitive adhesive
Security seal	Confidential mail	Patterned adhesive that reveals tampering

Production standard: adhesive strip must be 100% uniform, with no gaps wider than 0.5 mm and no bleed-through visible on the front panel.

Quality Control Checklist (Factory Standard)

Every batch of custom #10 envelopes is checked against these criteria before shipment:

Dimensions — spot-checked against the 4⅛ × 9½ in standard (±1.6 mm tolerance)
Registration — print colors aligned within 0.1 mm
Color accuracy — ΔE ≤ 2.0 against approved proof
Cutting — no frayed edges, clean corners, consistent flap fold
Gumming — uniform adhesive, correct moisture content
Sampling — AQL 2.5 general inspection level on every order

Common #10 Envelope Design Mistakes to Avoid

No bleed — white edges appear when trimming shifts ±1 mm
Address area covered by graphics — interferes with postal sorting and barcoding
Low-resolution logos — 72 DPI artwork looks soft at 300 DPI print
Text inside the 6 mm safe margin — risk of clipping in the fold/trim
Wrong window position — the address block misses the window entirely

FAQ

What size is a #10 envelope?
A #10 envelope measures 4⅛ × 9½ inches (105 × 241 mm) — the standard US business envelope size.

What fits inside a #10 envelope?
A standard US letter (8½ × 11 in) folded into thirds. A4 paper also fits when folded into thirds, though slightly more snugly.

What is the difference between a #9 and a #10 envelope?
The #9 (3⅞ × 8⅞ in) is smaller and typically used as a reply envelope inserted inside a #10. The #10 is the standard mailing envelope.

Can I order custom printed #10 envelopes in small quantities?
Yes — our factory supports runs from a few thousand to millions of units. Small runs are printed digitally; large runs use offset for the lowest bulk envelope pricing.

Do you make #10 envelopes with a window?
Yes, window #10 envelopes with single or double windows are standard production items, positioned per USPS automation requirements.

How much does a custom #10 envelope cost?
Cost depends on quantity, paper, and print process. For a factory-direct quote on custom #10 envelopes, request a quote — we respond within 24 hours with per-unit pricing.