About Stamp Calculator

Stamp Calculator is an independent editorial and utility site focused on one problem: helping people estimate domestic USPS First-Class postage for common letters, postcards, and large envelopes (flats) using the same retail rate tables you would look up in USPS Notice 123.

What we publish

The core product is a set of free calculators and scenario pages: you enter weight, dimensions, and a few handling flags, and the site applies letter vs flat rules that match our published limits, then shows a dollar total and stamp-style combinations where that is helpful. We also publish longer guides for mailing scenarios—wedding invitations, large envelopes, square mail, and similar topics—written for readers, not for keyword lists.

What we are not

We are not the United States Postal Service, and we are not a postage vendor. We do not print labels, sell stamps, or guarantee that a clerk will agree with every edge case. International mail, retail discounts (metered or commercial), and zone-based parcels are outside the scope of this site's pricing logic—use usps.com or a Post Office for those products.

How rates are maintained

Letter, flat, and postcard amounts are updated in one place in the codebase when USPS adjusts Notice 123 retail rows, with a visible rate version on the site. When in doubt, treat official USPS sources as authoritative and confirm important mail at retail.

Advertising

The site may display ads (for example through Google AdSense) and may include affiliate links where they genuinely help readers buy supplies. Ads do not change how the calculators work. See the Privacy Policy for analytics and cookies.

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