Postage Calculator
Weigh the letter, pick the class and destination, and get a friendly estimate of the postage — so a young letter-writer knows how many stamps to grab before the trip to the mailbox.
Postage, made simple for kids
Postage feels like a mystery until you break it into three questions: how heavy is it, what shape is it, and how far is it going? A plain one-ounce letter is the cheapest thing to send; heavier notes, square cards, and small parcels cost more, and a letter crossing a border costs more again. Working the number out together turns a chore into a little maths lesson.
Once you know the postage, use the Stamp Quantity calculator to count how many stamps to stick on, or the Mail Delivery Time estimator to guess when it will arrive.
Frequently Asked Questions
How much does it cost to mail a normal letter?
A standard one-ounce letter — a single folded sheet in an envelope — is priced at the base first-class rate, and each additional ounce adds a small charge up to the 3.5-ounce letter limit. This calculator reads the USPS retail price list (Notice 123, effective July 12, 2026) so a family can see, before licking a stamp, what a letter will cost to send at home or abroad.
Why does a birthday card sometimes cost extra?
Two reasons: weight and shape. A card with a thick insert, a small keepsake, or a lot of glitter can tip past one ounce, a square, stiff or lumpy card pays a nonmachinable surcharge on top of the letter price, and anything larger than 6-1/8 by 11-1/2 inches or thicker than a quarter inch is charged as a large envelope. If your card is oversized or thick, choose the large-envelope class here to see the higher price.
Are these prices exact?
They are the USPS retail prices from the price list effective July 12, 2026. Where the price depends on the exact country or distance, the calculator shows the highest price in that range, so a letter stamped to it is not short. Prices change, usually each January and July, and extras like tracking cost more: confirm the current price at the counter or on usps.com before you buy stamps.
How do I weigh a letter at home?
A kitchen scale works well: place the sealed envelope on it and read the ounces. As a rule of thumb, a standard envelope holding up to about four sheets of ordinary printer paper stays under one ounce; card stock, photos and stickers add weight quickly. When in doubt, weigh it: a stamp too many is cheaper than a letter returned for postage.
USPS retail prices from Notice 123, effective July 12, 2026. Prices change with each rate update and extra services cost more: confirm the current price at the counter before buying stamps.