Yes, you can put two stamps on an envelope. The U.S. Postal Service allows “any combination of stamps” as long as the total face value meets or exceeds the postage owed on the mailpiece.1United States Postal Service. How to Send a Letter or Postcard A single Forever stamp at $0.78 covers a standard one-ounce letter, so most everyday mail only needs one.2United States Postal Service. First-Class Mail and Postage Doubling up is the easy fix when your envelope is heavier, larger, oddly shaped, or headed overseas.
When Two Stamps Make Sense
Weight is the usual reason. A First-Class letter can weigh up to 3.5 ounces, and each ounce beyond the first adds to the base rate.2United States Postal Service. First-Class Mail and Postage A couple of pages will stay under an ounce; add photos, a gift card, or thicker cardstock and you cross the line. Two Forever stamps give you $1.56 of postage, which covers a heavier standard letter with margin.
Size is the other trigger. If you’re sending 8½-by-11 pages unfolded, you need a large envelope, or “flat.” Postage on flats starts at $1.63, so one Forever stamp falls short and three ($2.34) will more than cover it.1United States Postal Service. How to Send a Letter or Postcard Flats can weigh up to 13 ounces and still go First-Class.2United States Postal Service. First-Class Mail and Postage
You may also just want to use up older stamps in a drawer. Combining two lower-value stamps to exceed the current rate is fine. USPS won’t refund the overage, but the letter goes.
Current First-Class Rates
Knowing the baselines lets you figure out how many stamps to put on:
- Standard letter, one ounce: $0.78, the price of a Forever stamp.2United States Postal Service. First-Class Mail and Postage
- Large envelope or flat, one ounce: starts at $1.63.1United States Postal Service. How to Send a Letter or Postcard
- Nonmachinable surcharge: an added $0.49 on qualifying letters.1United States Postal Service. How to Send a Letter or Postcard
- International letter, one ounce: $1.70, the price of a Global Forever stamp.3United States Postal Service. First-Class Mail International
When you’re unsure, weigh the envelope on a kitchen scale and check the USPS postage calculator or ask at the counter.
The Nonmachinable Surcharge
Even under an ounce, some envelopes cost more. The nonmachinable surcharge adds $0.49, pushing a standard letter to $1.27 total.4United States Postal Service. Mailing and Shipping Prices One Forever stamp won’t cover that; two will.
An envelope is nonmachinable if it has any of these features:
- A square shape, or a length-to-height ratio under 1.3 or over 2.5.5United States Postal Service. 3-6 Nonmachinable Criteria
- Rigid or lumpy contents like pens, keys, or coins.5United States Postal Service. 3-6 Nonmachinable Criteria
- Clasps, strings, or buttons as closures.5United States Postal Service. 3-6 Nonmachinable Criteria
- A plastic exterior or polywrap; paper windows are fine.5United States Postal Service. 3-6 Nonmachinable Criteria
- Rigidity that keeps it from bending through the sorter’s rollers.
Wedding invitations hit almost all of these. A square envelope with a rigid insert and a wax seal is a classic two-stamp job.
Using Two or Three Domestic Stamps on International Mail
A one-ounce letter to any country costs $1.70.3United States Postal Service. First-Class Mail International Without a Global Forever stamp on hand, three domestic Forever stamps ($2.34) will get it there. You overpay by $0.64, but the letter goes. If you send international mail regularly, buying Global Forevers is cheaper per piece.
Where to Place Multiple Stamps
All stamps go in the upper-right corner of the address side. The USPS International Mail Manual states that postage “must be applied to the address side of mail in the upper-right corner,” and domestic mail uses the same standard.6Postal Explorer. International Mail Manual – 153 Placement of Postage
Line the stamps up neatly so they don’t overlap or drift toward the address block. Sorting machines scan defined zones for the address, barcode, and postage; stamps that stray into the wrong zone can cause misreads and delays. Press each one down firmly so the edges don’t lift in transit.
Stamped Mail Over 10 Ounces Has to Be Handed Over the Counter
If you’re piling on stamps to cover something heavy, watch this rule. Any mailpiece paid entirely with stamps that weighs more than 10 ounces or is thicker than half an inch cannot go in a collection box, a lobby drop, or a personal mailbox. It has to be handed to an employee at a post office retail counter.7United States Postal Service. Publication 52 Revision – Stamp Mailpieces Over 10 Ounces
Your carrier can’t take it either, not even through Pickup on Demand. Drop it in a blue collection box and it will be returned to you.7United States Postal Service. Publication 52 Revision – Stamp Mailpieces Over 10 Ounces The restriction doesn’t apply if you use a meter, online postage, or a permit imprint, because those methods tie the mail to an identifiable account.8United States Postal Service. IMM Revision – Changes to Anonymous Mail Characteristics
If You Get the Math Wrong
Underpay with a return address on the envelope, and USPS marks it “Returned for Additional Postage” and sends it back to you. You add the shortfall, cross out the notice, and remail it.9United States Postal Service. Domestic Mail Manual – P011 Payment
With no return address, or if the shortage is caught at the destination, the letter is delivered marked with the amount owed. The recipient has to pay the difference in cash before the carrier hands it over.9United States Postal Service. Domestic Mail Manual – P011 Payment Not a great look for business mail.
Overpay and there’s no delivery problem: the letter arrives normally, and you don’t get the difference back. The USPS refund program covers things like non-delivery caused by USPS error, not voluntary stamp overpayment.10United States Postal Service. Request a Domestic Refund For one letter, wasting $0.78 on a spare Forever stamp is trivial. If you’re mailing in volume, additional-ounce stamps or an online postage service will pay exact rates.