About Seller Math

Seller Math is a free reference for people running small online shops, starting with Etsy. It's run by BlackHeaven Inc., which runs Etsy shops of its own - we built the calculator for ourselves first.

Seller Math is not affiliated with Etsy. It gives general information, not tax or accounting advice.

How this site is made

The guides here were written for this site by BlackHeaven Inc. Some newer articles are drafted with AI help; those are marked on the page, and they only appear after passing automatic checks for length, originality against our other pages, and claims we won't make. Numbers that change (fees, platform limits, prices) carry the date they were checked - please confirm them at the source before you rely on them. Spotted a mistake? Tell us at jarvis.blackheaveninc.app.

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This site is paid for by ads. Ads from other businesses are labelled Sponsored; ads for BlackHeaven's own products are labelled From BlackHeaven. Advertisers never pay for, write or approve our articles.