Why 2 oz is a common search
Many home mailers stop at one ounce in their head—“one stamp”—but a folded sheet, a card stock invite, or a few pages pushes the piece to two ounces quickly. Searchers often want a fast rule: Forever plus additional ounce. This calculator adds the envelope dimensions so you do not miss the moment when the same weight would still fail as a letter because the piece is too thick or too large—then it is a large envelope, not a letter, and different rules apply.
How rounding works
USPS rounds postage weight up to the next whole ounce. A piece that weighs 1.1 oz is billed as 2 oz. Our notes call out the rounded weight so you can align the calculator with what your scale shows. If you are right on the line, weigh again: a few tenths of an ounce can change how many additional ounce stamps you need once you cross into the next bracket.
When “2 oz” is not a letter
Weight is only one test. If your envelope is too thick, too long, or otherwise outside letter limits, the Postal Service may treat the piece as a flat. In that case, the “how many stamps for 2 oz” answer for letters no longer applies. Use the size fields above; if you see the large-envelope message, stop using letter-stamp math and check flat rates (we will add flat pricing here in a future update).
Practical tips before you mail
Use a scale. Tape and decorative elements add weight. If you are sending something important, consider buying postage online or at the retail counter so you get a barcode that proves payment. Stamps are convenient; precision matters when the piece is heavy or oddly shaped.
Two ounces is also where many people discover that “almost letter” mail is not a letter at all. A rigid photo mailer can be under four ounces but still fail letter thickness or flexibility tests. If the calculator flags a large envelope, do not split the difference with letter stamps—either buy the correct flat postage or repackage into a thinner, flexible envelope that truly meets letter standards.
Business mailers sometimes send two-page letters on heavier paper that lands near two ounces even when the content feels routine. If you print on cardstock, fold brochures, or include a reply envelope inside the outer envelope, weigh the finished mailpiece. The two-ounce answer—“one Forever, one additional ounce”—is only correct when USPS still treats the item as a letter and when your rounded weight truly sits in the two-ounce bucket after rounding up.