Why we built these
Most online calculators bury the math under ads and email-capture walls. These don't: every tool on this page runs entirely in your browser, sends nothing anywhere, and shows its assumptions in plain text under the results. They use the same engines as the SheetWell templates — the spreadsheets simply keep your numbers and history where a web page can't.
Frequently asked questions
- Are these calculators really free?
- Yes — free, no signup, no email, and your numbers never leave your browser. They're how we show the quality of the math behind our paid templates.
- Do the calculators store my data?
- No. Everything runs locally in your browser with plain JavaScript; refresh the page and it's gone. If you want your numbers kept month after month, that's what the spreadsheet templates are for.