Introduction
The A-series is the invitation and stationery envelope family, running from A1 through A10 and keyed to card and photo sizes rather than folded letter paper. It’s the family behind wedding invitations, announcements, RSVP cards, and thank-you notes.
This guide covers the A-series from A1 to A10, plus the closely related baronial formats, with dimensions and what each one holds. For the invitation-etiquette side, see our invitation envelope sizes guide; for the broader family overview, our different envelope sizes piece.
The A-Series at a Glance
The A-series is sized to common card and photo formats.
| Size | Dimensions | Typical insert |
|---|---|---|
| A1 | 3⅝” × 5⅛” | Small RSVP, place card |
| A2 | 4⅜” × 5¾” | 4×5½ card |
| A4 | 4¾” × 6½” | 4½×6¼ card |
| A6 | 4¾” × 6½” | 4×6 photo/card |
| A7 | 5¼” × 7¼” | 5×7 card |
| A8 | 5½” × 8⅛” | Larger invitation |
| A9 | 5¾” × 8¾” | Large announcement |
| A10 | 6″ × 9½” | Folded letter |
The most-used sizes are A2, A6, and A7:
| Size | Why it’s common |
|---|---|
| A2 | Thank-you notes, RSVPs |
| A6 | 4×6 photos, invitations |
| A7 | 5×7 invitations |
Announcement Sizes
Announcement envelopes are the A-series sizes used for invitations and announcements.
| Size | Dimensions | Use |
|---|---|---|
| A2 | 4⅜” × 5¾” | Invitation, note |
| A6 | 4¾” × 6½” | Invitation, 4×6 |
| A7 | 5¼” × 7¼” | 5×7 invitation |
| A9 | 5¾” × 8¾” | Large announcement |
The distinction is the insert’s folded or flat state:
| Insert | Envelope |
|---|---|
| 4×5½ card | A2 |
| 4×6 photo | A6 |
| 5×7 card | A7 |
| Large flat announcement | A9 |
Baronial Sizes
Baronial envelopes have a deep pointed flap and a more formal, traditional feel, often used alongside the A-series.
| Baronial | Dimensions | Use |
|---|---|---|
| #2 | 4½” × 5¾” | Invitations |
| #4 | 3⅝” × 5⅛” | RSVP, place card |
| #5 | 4⅛” × 5½” | Small notes |
| #6 | 4¾” × 6½” | Invitations, cards |
Baronial vs A-series:
| Trait | Baronial | A-Series |
|---|---|---|
| Flap | Deep pointed | Varies |
| Feel | Formal, traditional | Modern, versatile |
| Common use | RSVP, formal | General stationery |
Card Envelope Sizes
Small card envelopes round out the family for compact stationery.
| Size | Dimensions | Holds |
|---|---|---|
| A1 | 3⅝” × 5⅛” | Place card, small RSVP |
| A4 | 4¾” × 6½” | 4½×6¼ card |
These small sizes serve place cards and compact reply cards.
| Use | Envelope |
|---|---|
| Place card | A1 |
| Small RSVP | A1 or #4 |
| Compact card | A4 |
Choosing the Right A-Size
Match the insert to the A-size.
| Your card/photo | A-Size |
|---|---|
| 4×5½ card | A2 |
| 4×6 photo | A6 |
| 5×7 card | A7 |
| Large announcement | A9 |
| Place card | A1 |
For 4×6 photo mailing specifically, see our envelopes for 4×6 guide.
Conclusion
The A-series envelope sizes — A1 through A10 — are the invitation and stationery family, keyed to card and photo sizes. A2 fits thank-you notes and RSVPs, A6 fits 4×6 photos, and A7 fits 5×7 invitations; baronial formats (#2–#6) add a formal, pointed-flap alternative. Match the insert to the size, and use the full list of envelope sizes for the complete lookup.
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