5x5 Square Envelope Postage
A 5 x 5 in square envelope needs $1.31 at 1 oz: the $0.82 letter price plus the $0.49 nonmachinable surcharge that every square letter pays.
Your answer
Nonmachinable letter
+$0.49 surchargeLetter postage plus the nonmachinable surcharge, because it has to be sorted by hand.
- Postage per piece
- $1.31
- 100 invitations
- $131.00
Stamps for each one
1 × Three-Ounce
That pays $0.09 more than needed. For exact postage, ask the post office counter to make up $1.31.
Why
- Square envelopes fail the aspect ratio rule: length divided by height must be between 1.3 and 2.5, and a square is 1. USPS rule
Save money: Switch to an A7 rectangle (5.25 x 7.25 in) and save $49.00 on 100 pieces, as long as the weight stays the same.
Rates last verified on
100 invitations: $131.00 in postage ($1.31 each, nonmachinable letter)
The smallest mailable square
A letter has to be at least 5 in long. A square is as high as it is long, so 5 x 5 in is the smallest square envelope the post office will take. A 4 3/4 in or 4 1/2 in square, both sold for small cards, is not mailable by itself at any price.
If your card needs a smaller square envelope, it has to travel inside something larger.
The minimum applies to the finished envelope, not the card inside it. Check the outside measurement of the envelope itself, since shop listings often quote the card size.
Why the surcharge applies
Sorting machines find the address by assuming the envelope is longer than it is tall. The rule is that length divided by height must be at least 1.3. A square is exactly 1, so the machine cannot tell which way is up and the piece is sorted by hand. More on square envelopes.
The surcharge is the same at every weight: $1.31 at 1 oz, $1.60 at 2 oz.
Putting a small square card in a rectangle
A 4 3/4 in square card fits inside an A7 envelope, which mails at the plain letter price. You lose the matched look and gain $0.49 per piece. On 100 cards that is $49.00.
If the square envelope is the point of the design, pay the surcharge and enjoy it. Once you are paying it, a wax seal or ribbon adds nothing more.
Which stamps make up the price
No common single stamp is worth exactly $1.31. A Three-Ounce stamp is worth $1.40, which covers a 1 oz square envelope with $0.09 to spare. Two Forever stamps cover it too, overpaying $0.33. For exact postage, a post office counter can print a label.
Compare the options
| Option | Mail class | Each | For 100 |
|---|---|---|---|
| 5 x 5 square envelope, 1 oz | Nonmachinable letter | $1.31 | $131.00 |
| 4.75 x 4.75 square envelope, 1 oz | Not mailable as is | Not mailable | - |
| Same card in an A7 rectangle, 1 oz | Standard letter | $0.82 | $82.00 |
| 5 x 5 square with a wax seal, 1 oz | Nonmachinable letter | $1.31 | $131.00 |
Questions and answers
How much postage does a 5x5 envelope need?
$1.31 at 1 oz, which is $0.82 letter postage plus the $0.49 nonmachinable surcharge.
Can I mail a square envelope smaller than 5 inches?
No. Letters must be at least 5 in long, so a square under 5 x 5 in is not mailable.
Will two Forever stamps cover a 5x5 square envelope?
Yes at 1 oz. Two Forever stamps are worth more than the $1.31 needed, so you overpay slightly.