6x6 Square Envelope Postage
A 6 x 6 in square envelope is a nonmachinable letter: $1.31 at 1 oz, $1.60 at 2 oz. It is the largest common square that is still priced as a letter.
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 A10 rectangle (6 x 9.5 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)
Just inside the letter limit
Letters can be up to 6 1/8 in high. A 6 in square is under that by 1/8 in, so it is a letter, and because it is square it pays the $0.49 nonmachinable surcharge.
Squares larger than 6 1/8 in stop being letters. They are large envelopes, with no surcharge but a higher starting price of $1.69. So a 6 in square at 1 oz costs $1.31, and a 6 1/2 in square at 1 oz costs $1.69. If you are choosing between those two, the smaller one saves $38.00 per 100.
Measure the envelope you actually have
With only 1/8 in to spare, the label on the box is not enough. Some "6 x 6" envelopes are cut at 6 1/4 in to give a 6 in card room. That quarter inch moves the piece into large envelope pricing. Lay a ruler across one before ordering in bulk.
Weight on a 6 in square
A 5 3/4 in square card has noticeably more paper than a 5 x 7, and a square suite usually has square inserts to match. Two-ounce totals are common, which makes the typical cost $1.60 each.
Past 3.5 oz the piece pays large envelope prices anyway, and the surcharge drops away because it only applies to letters.
The rectangle alternative
A 5 3/4 in square card fits an A10 envelope, 6 x 9 1/2 in, which is a normal letter. At 2 oz that is $1.11 instead of $1.60, saving $49.00 per 100. The card will have room to slide lengthwise, so add a backing card or band to hold it centered.
Compare the options
| Option | Mail class | Each | For 100 |
|---|---|---|---|
| 6 x 6 square, 1 oz | Nonmachinable letter | $1.31 | $131.00 |
| 6.25 x 6.25 square, 1 oz | Large envelope (flat) | $1.69 | $169.00 |
| 6 x 6 square, 2 oz | Nonmachinable letter | $1.60 | $160.00 |
| A10 rectangle (6 x 9.5 in), 2 oz | Standard letter | $1.11 | $111.00 |
Questions and answers
How much postage does a 6x6 envelope need?
$1.31 at 1 oz and $1.60 at 2 oz, including the $0.49 nonmachinable surcharge.
Is a 6x6 envelope a letter or a flat?
A letter, because it is under 6 1/8 in high. A square larger than 6 1/8 in is a flat, also called a large envelope.
What rectangle fits a 5.75 inch square card?
An A10 envelope, 6 x 9 1/2 in, fits it and mails at the plain letter price.