Envelope Sizes Chart
Standard envelope sizes and dimensions in inches and millimeters. Find the right envelope for letters, cards, and invitations.
| Envelope | Inches | Millimeters | Best for |
|---|---|---|---|
| #10 Business | 4.125" × 9.5" | 105 × 241 | Business letters, invoices |
| #9 Business | 3.875" × 8.875" | 98 × 225 | Reply envelopes |
| #6¾ Personal | 3.625" × 6.5" | 92 × 165 | Personal notes, checks |
| A2 Card | 4.375" × 5.75" | 111 × 146 | RSVP, greeting cards |
| A6 Card | 4.75" × 6.5" | 121 × 165 | Invitations, cards |
| A7 Greeting | 5.25" × 7.25" | 133 × 184 | Greeting cards, photos |
| A9 | 5.75" × 8.75" | 146 × 222 | Large cards, photos |
| 5x7 | 5" × 7" | 127 × 178 | Photos, invitations |
| C5 | 6.375" × 9" | 162 × 229 | A4 folded, catalogs |
| C6 | 4.5" × 6.375" | 114 × 162 | A5 folded, cards |
| DL | 4.33" × 8.66" | 110 × 220 | A4 folded in thirds |
Source: USPS standard sizes for North America & ISO 216 (C5, C6, DL) for international envelopes.
How to choose the right envelope dimensions
Letters & invoices
#10 is the standard envelope format for business mail. It fits an 8.5" × 11" letter folded into thirds — the standard letter size envelope for letters and invoices.
Cards & invitations
A2 and A6 hold 4x6 cards; A7 fits 5x7. Always pick an envelope about ¼" larger than your card.
International
C5, C6, and DL are ISO sizes for A-series paper — common outside the US and Canada.
Found your size? Print addresses on it with the free tool, or grab a matching envelope template.
Envelope size FAQ
What is the standard envelope size?
The #10 business envelope (4.125" × 9.5") is the most common standard envelope size. It holds a standard letter folded into thirds.
What size is a #10 envelope?
A #10 envelope is 4.125 inches × 9.5 inches (105 × 241 mm). It's the standard size for business letters and invoices.
What envelope size fits a 5x7 card?
An A7 envelope (5.25" × 7.25") fits a 5x7 card with a little room to spare. It's the standard for greeting cards and invitations.
What is the difference between A2 and A6 envelopes?
A2 is 4.375" × 5.75" (RSVP size). A6 is larger at 4.75" × 6.5" (for 4x6 cards). Both are common invitation sizes.
What is a DL envelope?
A DL envelope is 110 × 220 mm (4.33" × 8.66"). It's the standard European size for A4 paper folded into thirds, similar to the US #10.
What envelope size fits a letter-size paper?
A #10 business envelope (4.125" × 9.5") is the standard letter-size envelope. It fits an 8.5" × 11" sheet folded into thirds, which is why it's the default for business mail.
What are the standard envelope dimensions?
The standard US business envelope (#10) is 4.125 × 9.5 inches (105 × 241 mm). Common card sizes are A2 (4.375" × 5.75"), A6 (4.75" × 6.5"), and A7 (5.25" × 7.25").
What is the average envelope size?
For most letters and invoices, the average envelope size is #10 (4.125" × 9.5"). For cards and invitations, typical envelope sizes run A2 through A7 depending on the card dimensions.
What are std envelope sizes?
Std envelope sizes for US business mail are the #10 (4.125" × 9.5"), #9, and #6¾ personal sizes. Card envelopes use the A-series (A2, A6, A7) and 5x7.
What is the letter format envelope?
The letter format envelope is the #10 business envelope, sized 4.125" × 9.5". Its letter size envelope dimensions fit an 8.5" × 11" sheet folded into thirds — the standard letter envelope format for US mail.
What envelope size for letter size paper?
The #10 is the envelope size for letter size paper, holding an 8.5" × 11" sheet folded in thirds. Its dimensions standard envelope is 4.125 × 9.5 inches (105 × 241 mm).