How Many Stamps for a Manila Envelope?

If you're wondering how many stamps for a manila envelope, a 1 oz domestic large envelope needs $1.69 in postage as of October 4, 2026. That takes three standard Forever stamps worth $0.82 each as of that date; two aren't enough. The count changes with the filled envelope’s weight, and rigid or lumpy contents can require package pricing.

How Many Stamps for a Manila Envelope by Weight?

A manila envelope qualifying as a domestic First-Class Mail flat needs three to seven standard Forever stamps for weights up to 13 oz, using October 4, 2026 rates. Weigh the complete envelope, select its weight tier, and use enough stamps to cover the full postage.

The table uses the USPS Notice 123 price list dated October 4, 2026. All postage amounts, excess amounts and stamp counts below use the standard Forever stamp’s $0.82 value as of October 4, 2026.

Filled Envelope Weight, Not Over	Flat Postage	Standard Forever Stamps Needed	Excess Postage With Those Stamps
1 oz	$1.69	3	$0.77
2 oz	$1.98	3	$0.48
3 oz	$2.27	3	$0.19
4 oz	$2.56	4	$0.72
5 oz	$2.85	4	$0.43
6 oz	$3.14	4	$0.14
7 oz	$3.43	5	$0.67
8 oz	$3.72	5	$0.38
9 oz	$4.02	5	$0.08
10 oz	$4.32	6	$0.60
11 oz	$4.62	6	$0.30
12 oz	$4.93	7	$0.81
13 oz	$5.24	7	$0.50

Use the next weight tier whenever the envelope exceeds a row’s limit. An envelope weighing 2.1 oz uses the 3 oz row, even though it’s closer to 2 oz.

These are domestic First-Class Mail flat rates. The table doesn’t cover packages, international mail or extra services.

Why a 9 × 12 Manila Envelope Is a Flat

The USPS physical standards limit letter-size mail to 11½ inches long, 6⅛ inches high and ¼ inch thick. A 9 × 12-inch envelope exceeds the letter dimensions even with one sheet inside. It qualifies for flat pricing when the filled envelope also meets the flat requirements.

Flats must be rectangular, flexible and uniformly thick, with maximum dimensions of 15 inches long, 12 inches high and ¾ inch thick. The longest side is the length. A rigid backing, a bulky object or contents gathered into a lump can make a large envelope a package. Adding a letter nonmachinable surcharge doesn’t make that package eligible for flat pricing.

Smaller manila envelopes may qualify as letters. Letter-size pieces with clasps, string closures, excessive rigidity or uneven contents can incur the $0.49 nonmachinable surcharge as of October 4, 2026. For those mailpieces, use our guide to how many stamps you need to check letter postage.

Stamp Combinations Can Avoid Excess Postage

Using standard Forever stamps alone is straightforward, but the total often exceeds the required postage. You can combine unused stamps of different denominations to reach the exact amount instead. At October 4, 2026 rates:

• 1 oz flat: Two standard Forever stamps total $1.64. Add 5¢ in denomination stamps to reach $1.69 exactly. Three standard Forever stamps total $2.46, or 77¢ above the required postage.
• 3 oz flat: Three standard Forever stamps total $2.46 against $2.27 required, leaving 19¢ in excess postage.
• 12 oz flat: Six standard Forever stamps total $4.92, which is 1¢ short of the $4.93 required. Add enough postage to cover the difference, or use seven standard Forever stamps.

The number of stamps isn’t the deciding factor; their combined postage value is. If you’re using additional-ounce stamps in a combination, our additional-ounce postage guide explains how they contribute toward the total.

If you also send smaller manila envelopes that qualify as letters, browse our two-ounce postage stamps. These cover two-ounce letter postage; a single two-ounce stamp doesn’t cover a two-ounce flat.

Weigh at Home or at the Post Office

Weigh at home when you’re mailing flexible documents in an envelope that clearly meets flat requirements and your scale can distinguish between weight tiers. Weigh the complete mailpiece, including the envelope, papers, labels and inserts. Sheet count alone won’t give you a reliable postage amount because paper and envelope weights vary.

Use the Post Office counter when your scale rounds to whole ounces, the reading is close to a cutoff, or the filled envelope’s stiffness or unevenness makes its classification uncertain. Bring the prepared envelope before attaching stamps so the clerk can assess its weight and category. First-Class Mail flats have a 13 oz maximum; heavier envelopes need another service.

For repeated mailings, weigh an envelope from each different set of contents. An extra form, return envelope or protective insert can move one mailing into a higher weight tier even when every outer envelope is the same size.

FAQ

Are Manila Envelopes Always Large Envelopes?

No. A small manila envelope may qualify as a letter, while a large envelope with rigid or lumpy contents may require package pricing.

Does the Envelope’s Weight Count?

Yes. Postage is based on the complete mailpiece, including the envelope, papers, labels and inserts.

Does the Table Include International Postage?

No. These stamp counts apply to domestic First-Class Mail flats; envelopes sent internationally need the applicable international postage.