#10 Envelope Postage
A #10 envelope is 4 1/8 x 9 1/2 in, the standard business envelope. At 1 oz it is a standard letter and needs $0.82.
Your answer
Standard letter
No extra postageRegular letter postage. No surcharge.
- Postage per piece
- $0.82
- 100 invitations
- $82.00
Stamps for each one
1 × Forever (1 oz letter)
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 2.3 (it must be between 1.3 and 2.5). USPS rule
Rates last verified on
100 invitations: $82.00 in postage ($0.82 each, standard letter)
The other end of the shape rule
Most invitation trouble comes from envelopes that are too square. The #10 sits near the opposite limit. Its length divided by height is 2.30, and the maximum is 2.5. It passes, but a longer or narrower envelope of the same family may not: at 4 1/8 in high, anything over 10 5/16 in long is nonmachinable.
That is worth knowing if you are looking at slim "money" or policy-style envelopes for a tall invitation. Too long and narrow costs the same $0.49 as too square.
Invitations in a #10
The #10 holds a letter sheet folded in thirds, which makes it handy for printed-at-home invitations, shower invites with a folded insert, and formal letters. It also takes tall 4 x 9 1/4 in cards; see the tea length page for those.
Card stock reaches the 1 oz line much sooner than copy paper does. If yours feels close, weigh it.
Window envelopes are fine
USPS says a window in a paper envelope does not make it nonmachinable. An envelope made of plastic, or a paper one sealed inside a clear sleeve, does.
Folding saves real money
A full letter-size sheet mailed flat needs a 9 x 12 in envelope. That is a large envelope and costs $1.69 at 1 oz. Folded in thirds in a #10, the same sheet is a letter at $0.82. On 100 pieces the fold saves $87.00.
The fold only stops paying off when the contents are thicker than 1/4 in once folded, or when they must not be creased, such as a certificate or a print.
Address direction
A #10 must be addressed along its 9 1/2 in side. Addressed along the 4 1/8 in side it reads as under 5 in long, which is not a surcharge but a refusal.
Compare the options
| Option | Mail class | Each | For 100 |
|---|---|---|---|
| #10 (4.125 x 9.5 in), 1 oz | Standard letter | $0.82 | $82.00 |
| Slim 4.125 x 10.5 in envelope, 1 oz | Nonmachinable letter | $1.31 | $131.00 |
| #10 in a clear plastic sleeve | Nonmachinable letter | $1.31 | $131.00 |
| #10 at 1.2 oz | Standard letter | $1.11 | $111.00 |
Questions and answers
How many stamps does a #10 envelope need?
One Forever stamp ($0.82) up to 1 oz. Add one Additional Ounce stamp ($0.29) for each extra ounce.
Is a #10 envelope machinable?
Yes. Its aspect ratio of 2.30 is inside the 1.3 to 2.5 range.
Can I address a #10 envelope along the short side?
No. USPS would read it as 4 1/8 in long, which is under the 5 in minimum, so it would not be mailable.