Collector tools · Stamps
Old stamps, exact postage.
List the stamps in your drawer and the postage you need. The calculator finds every way to reach it with the stamps you actually have, least overpayment first, fewest stamps next.
Postcrossing members have wanted this for years. In a February 2023 forum thread proposing that a stamp calculator go on the site, one member says working it out “sometimes takes a lot of time” and another says that with a regular calculator “you can’t see all the calculations that meet your criteria at once.” This is a small version of that tool: a bounded search over your own stock, with no stamp-value guide and nothing sent anywhere.
Short answer: the 2 oz stamped letter price is $1.11 (USPS Notice 123, effective 4 October 2026). With two 32¢, three 20¢, four 10¢, two 5¢, five 3¢ and ten 1¢ stamps, the fewest stamps that reach it exactly is 7: two 32¢, two 20¢, one 5¢ and two 1¢. Allow only 6 stamps and nothing adds up.
How the search works
The tool tries every count of every stamp value you list, up to how many you have and up to your limit on stamps, and keeps each combination whose total lands between the postage you need and that postage plus the extra you allow. It then sorts by extra postage, so exact matches come first, then by number of stamps, so the tidiest envelope leads. Leave a quantity blank when you have plenty of that stamp. Amounts are handled in whole cents, so $0.29 + $0.03 is exactly $0.32, not a floating-point near miss.
Current rates to aim for
USPS Notice 123, effective 4 October 2026, lists a stamped 1 oz letter at $0.82, 2 oz at $1.11, 3 oz at $1.40 and 3.5 oz at $1.69. A postcard is $0.65 and a 1 oz large envelope is $1.69. Type the figure for your piece into the postage box. Check Notice 123 again before mailing, because rates change.
Old stamps still count
The Domestic Mail Manual, section 604.1.2, says all postage stamps issued by the United States since 1860, unless listed in 1.3, are valid for postage. Section 1.3 is the exclusion list: postage due, special delivery and Certified Mail stamps, stamps of other countries, and stamps that are mutilated or defaced among them. The manual also says the total postage affixed must equal at least the postage charge, which is why this tool lets you allow a little extra instead of insisting on exact.
Room on the envelope
Section 1.7 requires stamps to be affixed in the upper right corner of the address side, and says a stamp partly concealed by an overlapping stamp may not be counted as postage. That is why the tool caps the number of stamps. The default of 6 is a starting point chosen here for readability, not a USPS limit, so raise it if your stock needs it.
Worked example
Target $1.11, a drawer of two 32¢, three 20¢, four 10¢, two 5¢, five 3¢ and ten 1¢ stamps, at most 8 on the envelope. The search finds 6 exact combinations. The shortest uses 7 stamps: 2 × 32¢ + 2 × 20¢ + 5¢ + 2 × 1¢ = 64 + 40 + 5 + 2 = 111¢. The drawer is invented for the example; the $1.11 is the real 2 oz price. Cut the limit to 6 stamps and the answer is none, which tells you to allow extra postage or find a different stamp.
What this page does not cover
It does not value stamps as collectibles, and it does not know other countries’ rates. Forever and other non-denominated stamps have no printed value to enter: the manual says a Forever stamp is worth the current 1 oz stamped letter price, so type that amount. The manual lists some non-denominated stamps at their original issue prices, so check section 1.2 for those.
Common mix-ups
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Often assumedOld stamps from a drawer or an inherited collection have expired and can no longer pay postage.
What the source saysThe Domestic Mail Manual says all postage stamps issued by the United States since 1860 are valid for postage, apart from the kinds excluded in section 1.3 such as postage due stamps, foreign stamps and defaced stamps. [1]
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Often assumedAny number of stamps can be stacked on an envelope as long as their values add up to the postage.
What the source saysSection 1.7 says a stamp partly concealed by an overlapping stamp may not be counted as postage, and stamps must go in the upper right corner of the address side. Overlapping stamps can lose their value. [1]
Checked against these sources on .
Frequently asked questions
Can I still use old stamps for postage?
Yes. The Domestic Mail Manual says stamps issued by the United States since 1860 are valid for postage, apart from the kinds listed in section 1.3.
What if I have lots of one stamp?
Leave its quantity blank. The search then limits it only by your maximum number of stamps.
Why allow extra postage?
The manual requires total postage of at least the charge. Overpaying a few cents can reach a combination exact matching cannot.
Can stamps overlap?
Not if you want them counted. A stamp partly hidden by another may not be counted as postage under section 1.7.
How many stamps fit on an envelope?
The manual only says where they go, the upper right corner of the address side. The number that fits depends on stamp size, so set your own maximum.
Does this work outside the United States?
The arithmetic does, but the rates and rules on this page are USPS ones. Enter your own postage and check your postal service.
Sources and how it is calculated
Retrieved
Rates are from Notice 123 and stamp rules from Domestic Mail Manual 604, both read on 26 October 2026. The forum quotes come from the Postcrossing thread above. The stamps in the worked example are invented.
- Postcrossing Community, “Suggestion - Putting the Stamp Calculator on the Postcrossing Website” (8 February 2023)
- USPS Postal Explorer, Notice 123 (effective 4 October 2026): stamped letter and postcard prices
- USPS Domestic Mail Manual 604, Postage Payment Methods: sections 1.2 (valid stamps), 1.3 (invalid), 1.7 (position and overlap)
Runs entirely in your browser. Nothing you type is sent or stored. Not affiliated with any mint, post office, forum or publisher named on this page.
Check the rate before you mail
Postage rates and stamp rules change. Confirm the amount with USPS or a post office, and weigh the piece, before relying on a combination from this page.