How many stamps does a mail club envelope need? USPS rates since July 12, 2026, with a calculator

Most mail club envelopes need one Forever stamp. The expensive surprises have nothing to do with weight: they come from how stiff the envelope is, what shape it is, and what is stuck on the outside. Below are the current USPS prices, the exact stamps for each case, and the checks to run on one packed envelope before you buy stamps for two hundred.

Rates checked on November 13, 2026 against the USPS price list (Notice 123), in force since July 12, 2026. The guide covers stamped mail inside the United States, with a section on mailing abroad.

Ad: this guide contains affiliate links. If you buy through them we earn a commission, at no extra cost to you. As an Amazon Associate we earn from qualifying purchases.

The stamp calculator

Start from what is in your envelope. If you have already weighed a packed one, type that weight in and it replaces the estimate.

USPS prices by envelope and weight

The whole price list a mail club needs fits in four rows. The envelope's size and stiffness pick the row, its weight picks the column.

The line between a letter and a large envelope is a size, not a name on the box. Anything up to 11.5 inches long, 6.125 inches high and a quarter inch thick is a letter (USPS Domestic Mail Manual, section 101).

How to find your envelope's postage, step by step

1. Pack one complete envelope. Everything that goes in the real one: print, letter, stickers, board, sleeve, address label and seal. A club mails hundreds of identical envelopes, so one sample answers for the whole month.
2. Weigh it. Any kitchen scale that reads to 1 g will do. The price steps are at 1, 2, 3 and 3.5 oz, which is 28, 56, 85 and 99 g. Within a gram or two of a step, treat it as over: paper stock, a label or a second stamp can tip it.
3. Measure it. Past 11.5 by 6.125 inches in either direction, it is a large envelope, which USPS also calls a flat.
4. Bend it. The USPS test for a large envelope: lay it half off the edge of a table and press down one inch from the outer edge. It has to bend at least an inch without damage (DMM 201, section 4.3). A letter, in the official wording, must bend easily around a turn 11 inches across. Sellers who mail cards for a living use a rougher version: if the cardboard won't easily wrap around a water bottle, it is too stiff (eBay community thread).
5. Check the thickness. A quarter inch is the limit for a letter. Paper alone rarely gets there. A zine, a board and a wax seal together can.
6. Look at the outside. A square shape, a wax seal, a clasp, string, a button or a plastic outer sleeve each add the $0.49 surcharge to a letter. You pay it once, even if several apply.
7. Buy the exact stamps. The price table above gives the combination for each case, and the calculator shows what you overpay with Forever stamps alone.
8. Mail one to yourself. It costs one stamp and it is the only way to see how your envelope comes out of the sorting machines.

What a club envelope weighs

Here is where club envelopes land. The weights are estimates, worked out from paper sizes and paper weights, so weigh your own.

Start with the first row. A print, a letter and a sticker sit about seven grams under the 1 oz line, which leaves room for one more light thing (a second sticker, a small card) before the price moves.

The third row is the trap. A backing board weighs about as much as the print it protects, and it is what makes an envelope stiff.

As for what clubs put inside: among the hundreds of clubs running on MailClubly, about seven in ten describe a letter, more than half stickers, about half prints, three in ten a postcard, and fewer than one in ten a zine. Wax seals are rare: about one club in a hundred.

The mistakes that cost money

Treating a 6x9 envelope as a large envelope

A 6x9 is 6 inches high, under the 6.125 inch limit, so it mails at letter prices. At least two of the pages that rank for this question class it as a large envelope. If your zine or A5 print fits a 6x9, a 2 oz envelope costs $1.11 where a large envelope would cost $1.98.

Putting two Forever stamps on a large envelope

Two Forever stamps are worth $1.64. A 1 oz large envelope costs $1.69, and so does a 3.5 oz letter. That leaves the envelope 5 cents short, and short-paid mail comes back. One Forever stamp plus three Additional Ounce stamps pays $1.69 exactly.

Mailing a square envelope at the normal price

The sorting machines need a rectangle at least 1.3 times longer than it is high. A square envelope is 1.0, so it always pays the $0.49 surcharge, whatever it weighs (DMM 101, section 1.2). The same goes for an address written along the short side.

Assuming a wax seal is free

The advice online goes both ways. A letterpress studio whose post ranks for this question says a wax seal needs no extra postage unless it adds weight or thickness (Sal Studios). The USPS store, on the page for its non-machinable stamp, names wax-sealed envelopes as what the stamp is for (USPS Postal Store). The rule behind it is uneven thickness: a bump on the outside can jam or tear in the machines.

No one has published how often the surcharge is enforced. The rule is on USPS's side, though, and a returned batch costs more than the surcharge. So budget $1.31, put the seal inside, or use a flat sticker seal.

alivia laura, who runs the Cozy Reader Club, switched to foil seal stickers after wax-seal stickers made her envelopes too thick (her video).

Sending a stiff large envelope

This is the expensive one. A stiff letter pays $0.49 more and stays a letter. A stiff large envelope stops being a large envelope: USPS says one that is rigid, not rectangular or lumpy must go at package prices (USPS, Letters), and the cheapest package at the counter is $8.40. A 9x12 print in a rigid mailer goes from about $2 to more than $8.

To mail a large print flat, you have three options:

• a flexible board that passes the table-edge test
• a smaller print that fits a letter-size envelope
• a price that covers a package

A plastic sleeve as the outer envelope

A letter whose outside is plastic pays the surcharge. The rule is about the exterior, so as we read it a clear sleeve inside a paper envelope is fine.

Counting a 5x7 card as a postcard

The $0.65 postcard price only applies up to 4.25 by 6 inches. A 5x7 card mailed without an envelope pays the letter price.

Buying cheap stamps online

USPS warns that stamps sold online at a big discount are usually counterfeit (USPS, February 2023), and since July 2023 mail carrying counterfeit postage is treated as abandoned (DMM 604, section 8.4). It is not returned to you, so a whole month's mailing can disappear that way.

Real discounts on letter postage are tiny: postage printed online or by a meter is 4 cents under the stamp.

What happens when the postage is short

Short-paid mail with a return address goes back to the sender marked "Returned for Additional Postage", and short-paid non-machinable letters are returned for the surcharge (DMM 604, section 8.1). The cost is more than the missing cents. On a 300-envelope mailing that should have carried the surcharge, the postage gap is $147. Then comes a second packing session and a month that reaches members late.

One eBay seller reports about a fifth of their envelope shipments coming back, and a clerk telling them that "no cardboard is acceptable" in an envelope sent at letter price (eBay community thread).

Stamped mail has no tracking

A stamped letter gets no tracking number, acceptance scan or delivery confirmation. When a member writes that their envelope never arrived, you resend on trust.

Brenna Lanning, whose sticker club passed 1,100 subscribers in its seventh month, lists the work of a club as "packing mail, customer service, resending mail" (Creative Lives in Progress). alivia laura prints a few extra of everything each month in case letters get lost, and sends a replacement when an envelope has not arrived after four weeks (her video).

So print a few spares every month, and say in your FAQ how long a member should wait before asking for a replacement.

Mailing stickers and art prints

Stickers. USPS says flexible flat items "such as stickers, photos, or trading cards" can go in a letter if the envelope stays flat, is not lumpy and is under a quarter inch thick (USPS, Letters). Two or three vinyl stickers in an ordinary envelope usually stay within one stamp (GoatLabels). What gets a sticker envelope flagged is the stiff card people add behind it.

Art prints. A 4x6 or 5x7 print on heavy card has some stiffness of its own, and inside an A6 or A7 envelope with a folded letter it travels as a 1 oz letter. Bigger than 5x7, choose the envelope before the print: an A5 print fits a 6x9 and stays a letter, while an 8x10 needs a 9x12 and becomes a large envelope. Either way the print has to survive bending, because the envelope has to bend.

For what each paper weighs and how it behaves, see the guide to printers, paper and the rest of the kit.

Mailing outside the United States

The prices are the simple part. A 1 oz letter costs $1.75 to any country, which is one Global Forever stamp. Two ordinary Forever stamps are 11 cents short. Above 1 oz the price depends on the destination:

Look at the second row before you set an international surcharge. A 1 oz envelope costs $0.93 more to send abroad than at home. A 2 oz envelope to Europe costs $2.39 more. A flat "$2 for international" covers the first and loses money on the second.

The written rule. USPS says international letters and large envelopes may contain documents only: "Items containing merchandise are prohibited in First-Class Mail International" (USPS customs FAQ). A letter you wrote is a document. A print or a sticker that a member paid for is merchandise on that definition, and the service USPS offers for merchandise is a package with a customs form, which starts at $19.40.

What sellers do. People who sell stickers report sending a few flexible ones abroad as ordinary letters (GoatLabels), and many clubs do the same with their envelopes. Nobody publishes how often such letters are stopped.

The rules are getting tighter. The United States ended its duty exemption for low-value goods arriving by post (Federal Register, June 2026), the European Union has charged a €3 duty on low-value parcels since July 1, 2026 (Eurofiscalis), and postal operators in several countries now state that letters are for documents.

That leaves three choices:

• Mail abroad as letters, and accept that the written rule does not cover you.
• Send packages, and charge what they cost.
• Start with the United States only and add other countries later. Plenty of small clubs start domestic.

Where to buy stamps, and what else you need

Buy stamps from USPS: at the counter, or online from the USPS Postal Store. Club runners describe buying $500 of stamps at a time at the post office (Katie Mai), or 800 to 1,000 stamps in one order (Fiorenza Art).

Keep three kinds on hand: Forever stamps, Additional Ounce stamps, and Global Forever stamps if you mail abroad.

Two things people look for do not exist. Pirate Ship sells package labels only, no postage for letters or large envelopes, as its own help page says (Pirate Ship support). And a club mailing a few hundred stamped letters gets no meaningful bulk discount: the saving comes from the envelope's format and weight.

The rest of the kit is short:

• A scale that reads to 1 g. Any digital kitchen scale(paid link) will do.
• Paper envelopes in a letter size. A7 envelopes(paid link) for 5x7 prints, 6x9 envelopes(paid link) for zines and A5 prints.
• Clear sleeves, if you use them, sized for the print(paid link) and always inside the paper envelope.
• Address labels. Sheets of 30 (the Avery 5160 layout) and a mail merge from the member list are the method club runners describe most often.

When the prices change next

USPS has filed no price change for stamps for January 2027, and industry trackers expect the next one in July 2027 (Walsworth, October 30, 2026). That July date is a forecast. When a new price list takes effect, the calculator, the table and this page will be updated.

Questions readers ask

How many stamps for a 6x9 envelope?

One Forever stamp up to 1 oz, and one Forever plus one Additional Ounce stamp ($1.11) up to 2 oz. A 6x9 envelope is letter size.

How many stamps for a 9x12 or manila envelope?

A 9x12 is a large envelope: $1.69 for 1 oz, $1.98 for 2 oz, $2.27 for 3 oz. In stamps, that is one Forever plus three, four or five Additional Ounce stamps. Three Forever stamps ($2.46) cover it up to 3 oz and overpay.

How many stamps per ounce?

One Forever stamp ($0.82) for the first ounce of a letter, then $0.29 for each ounce after that, up to 3.5 oz.

How many stamps for a 2 oz envelope?

$1.11 for a letter: one Forever stamp plus one Additional Ounce stamp. Two Forever stamps also work and overpay by 53 cents.

What is a non-machinable letter?

A letter the sorting machines cannot handle: square, too stiff to bend, uneven in thickness, closed with a clasp or string, or wrapped in plastic. It pays $0.49 on top of the normal price. USPS sells a Non-machinable stamp worth $1.31 that covers a 1 oz letter with the surcharge.

Can you mail a wax seal?

Yes. Budget the non-machinable price ($1.31 for 1 oz), or put the seal inside the envelope. See the section on wax seals for why the advice online disagrees.

Do Forever stamps expire?

No. Every US stamp issued since 1860 is still valid unless it is damaged (DMM 604), and a Forever stamp is always worth the current 1 oz price.

Can I drop club envelopes in a mailbox?

Yes, if each stamped piece is 10 oz or less and no thicker than half an inch (DMM 126), which covers any letter. For a few hundred at once, handing the tray over at the counter is kinder to the mailbox.