A10 Envelope Postage
An A10 envelope is 6 x 9 1/2 in. It is the largest common invitation envelope that still counts as a letter, from $0.82 at 1 oz.
Your answer
Standard letter
No extra postageRegular letter postage. No surcharge.
- Postage per piece
- $1.11
- 100 invitations
- $111.00
Stamps for each one
1 × Two-Ounce (often sold as a wedding stamp)
Why
- This is a standard letter: within 6.125 x 11.5 in, no thicker than 0.25 in, and length divided by height is 1.58 (it must be between 1.3 and 2.5). USPS rule
Rates last verified on
100 invitations: $111.00 in postage ($1.11 each, standard letter)
One eighth of an inch from a different price
Letters can be at most 6 1/8 in high. The A10 is 6 in. That 1/8 in is the whole margin between letter postage and large-envelope postage.
It matters because envelopes sold as "6 x 9" come in two kinds. A 6 x 9 1/2 in invitation envelope is a letter. A 6 1/2 x 9 1/2 in booklet envelope looks almost identical and is a large envelope, which costs $1.69 at 1 oz instead of $0.82. Over 100 pieces that is $87.00.
Big envelopes carry big weights
People pick an A10 for oversized invitations, booklets and multi-page programs. Those are rarely 1 oz. Budget for $1.11 or $1.40, and check the top of the range: a letter can weigh at most 3.5 oz. At 3.6 oz the piece pays the large envelope price of $2.56.
Shape and address
Length divided by height is 1.58, well inside 1.3 to 2.5. Addressed along the 6 in side, the same envelope reads as 6 in long and 9 1/2 in high, a ratio of 0.63, and picks up the $0.49 surcharge. Keep the address along the long side.
Booklets and the thickness limit
A multi-page program or a welcome booklet in an A10 can approach the 1/4 in letter thickness limit. Over it, the piece is a large envelope whatever it weighs: $2.27 at 3 oz instead of $1.40. Large envelopes must also be flexible and evenly thick, so a booklet with a hard cover or a thick spine on one side is a risk.
For a 3 oz letter, one Three-Ounce stamp is exact postage.
Compare the options
| Option | Mail class | Each | For 100 |
|---|---|---|---|
| A10 (6 x 9.5 in), 2 oz | Standard letter | $1.11 | $111.00 |
| 6.5 x 9.5 in booklet envelope, 2 oz | Large envelope (flat) | $1.98 | $198.00 |
| A10 at 3.6 oz | Large envelope (flat) | $2.56 | $256.00 |
| A9 (5.75 x 8.75 in), 2 oz | Standard letter | $1.11 | $111.00 |
Questions and answers
Is an A10 envelope a letter or a flat?
A letter. At 6 x 9 1/2 in it is just inside the 6 1/8 x 11 1/2 in letter limit.
How much postage does a 6x9 envelope need?
A 6 x 9 1/2 in envelope needs $0.82 at 1 oz and $1.11 at 2 oz. A 6 1/2 in high envelope is a large envelope and starts at $1.69.
What is the heaviest an A10 can be at letter prices?
3.5 oz, which costs $1.69. Above that it pays large envelope prices.
What fits an A10 envelope?
A card or booklet up to 5 3/4 x 9 1/4 in.