A Forever stamp pays the current price of mailing a one-ounce First-Class letter anywhere in the United States, no matter when you bought it or what you paid. One stamp currently costs $0.78, and that same stamp keeps working after future rate increases without any extra postage added.1United States Postal Service. First-Class Mail That is the whole idea behind how Forever stamps work: you buy a service, not a dollar amount.
Why the Price You Paid Doesn’t Matter
Look at a Forever stamp and you won’t see a cent value printed on it. Older stamps showed a fixed price, which is why people used to end up with drawers full of two- and three-cent stamps after every rate hike. A Forever stamp represents one unit of service instead: mailing a one-ounce First-Class letter. Whatever that service costs on the day you drop the envelope in the mailbox is what your stamp is worth, even if you bought it years ago at a lower rate.2United States Postal Service. Postage Stamps – The Basics
So a sheet bought at $0.73 still mails a letter today at $0.78. And every U.S. postage stamp issued since 1860 remains valid, so a book of Forever stamps you find in a desk in ten years will work the same as one bought this morning. The practical takeaway: buying ahead of an announced price increase is a small, risk-free way to lock in the lower rate.
What One Forever Stamp Covers
One stamp pays for a standard rectangular envelope weighing an ounce or less. To qualify as a letter for that single-stamp rate, the envelope has to fall within specific dimensions: between 5 and 11½ inches long, between 3½ and 6⅛ inches tall, and no more than ¼ inch thick.3United States Postal Service. Business Mail 101 – Sizes for Letters A #10 business envelope or a typical greeting card envelope fits easily.
Put the stamp in the upper right corner. That is where the sorting machines look for postage, and a stamp placed elsewhere can delay the letter or get it returned.4United States Postal Service. How to Send a Letter or Postcard – Domestic A return address in the upper left corner is strongly recommended so undeliverable mail can come back to you, though it isn’t strictly required on ordinary First-Class letters.5United States Postal Service. Addressing Mailpieces
When One Stamp Isn’t Enough
Weight is the usual reason. Each additional ounce beyond the first costs $0.29.6United States Postal Service. USPS Recommends New Prices A two-ounce letter needs $1.07 in postage, which you can cover with one Forever stamp plus an additional-ounce stamp, or with two Forever stamps if you don’t mind overpaying by $0.49. First-Class letters cap out at 3.5 ounces.7United States Postal Service. DMM 101 Physical Standards for Retail Letters, Flats, and Parcels
Larger envelopes, which the USPS calls “flats,” start at $1.63.1United States Postal Service. First-Class Mail A manila envelope of documents needs three Forever stamps at the current rate, totaling $2.34 and overpaying by $0.71. For flats you send often, buying exact postage at the counter or printing it online costs less.
The Nonmachinable Surcharge
Some letters can’t run through sorting machines, and those cost an extra $0.49 on top of regular postage.8United States Postal Service. Notice 123 – January 2026 Price Change This trips up a lot of people mailing wedding invitations. Your letter picks up the surcharge if it is square (length-to-height ratio below 1.3 or above 2.5), too rigid to bend around a curved surface, uneven in thickness because of items like keys or coins inside, closed with a clasp or string tie, or made of a non-paper surface like plastic.
A one-ounce square wedding invitation, for example, needs $1.27 in postage: $0.78 plus the $0.49 surcharge. One Forever stamp alone won’t do it, and the piece will come back to you or arrive postage-due.7United States Postal Service. DMM 101 Physical Standards for Retail Letters, Flats, and Parcels
Postcards
A Forever stamp gets a postcard delivered, but you’re paying the full letter rate for something the USPS charges less for. The Postal Service sells a separate Postcard stamp at a lower price. To qualify for the postcard rate, the card must be between 5 and 9 inches long, between 3½ and 6 inches tall, and between 0.007 and 0.016 inches thick.9United States Postal Service. 201 Quick Service Guide
International Letters Need a Different Stamp
A domestic Forever stamp does not, on its own, cover mail going overseas. A one-ounce international letter costs $1.70, and stacking three domestic Forever stamps to clear that ($2.34) wastes money.10United States Postal Service. First-Class Mail International
The Global Forever stamp is the right tool. It works on the same principle as the domestic version: one stamp mails a one-ounce letter to any country, and it holds its value through future price changes. It currently costs $1.70.11United States Postal Service. U.S. Postal Service Recommends New Prices for July
Where to Buy Them Without Getting Burned
The safest sources are your local Post Office and the USPS online store, both of which sell at face value. Look for the word “Forever” on the stamp face to confirm you’re getting the non-denominational version rather than a fixed-cent stamp. Grocery stores, pharmacies, and some bank ATMs also carry them, usually at face value, though the USPS notes it has no control over what private resellers charge.2United States Postal Service. Postage Stamps – The Basics
Real caution is warranted with individuals and unfamiliar online sellers. Counterfeit Forever stamps have become a real problem, particularly through social media marketplaces and third-party e-commerce sites. The United States Postal Inspection Service warns that stamps offered at 20 to 50 percent below face value are almost certainly fake, because the USPS does not sell stamps below face value.12United States Postal Inspection Service. Counterfeit Postage
The consequences go beyond losing what you spent. Mail bearing counterfeit postage is treated as abandoned and can be opened and discarded by the Postal Service. You might never learn that your letter didn’t arrive.12United States Postal Inspection Service. Counterfeit Postage
Warning signs when buying outside a Post Office or major retailer:
- Any price below face value, especially “bulk deals” on social media
- Sellers shipping from outside the United States
- Blurry printing, uneven perforations, or colors that look slightly off
- Missing security features: genuine stamps are printed on tagged paper that glows yellow-green under shortwave UV light, while counterfeits typically appear blue
Suspected counterfeits can be reported through the Postal Inspection Service’s Counterfeit Postage Reporting System.12United States Postal Inspection Service. Counterfeit Postage
Exchanging Stamps You Can’t Use
Stamps stuck together from humidity or otherwise unusable can be exchanged at a Post Office, but only under specific rules. You get an equal number of stamps in the same denomination, not cash. The stamps must have been on sale at Post Offices within the previous 12 months. Each customer is limited to $100 worth of postage per exchange, and quantities over $10 of the same denomination have to be returned in the format you bought them, whether that was a booklet, sheet, or coil. The denomination or “Forever” marking has to be visible, and stamps mutilated or defaced beyond recognition can’t be exchanged at all.13United States Postal Service. 604 Postage Payment Methods and Refunds