I built this because every finance calculator site I found had the same pattern: tool buried behind an email gate, or the calculator itself was fine but surrounded by so much ad clutter it was unusable on mobile. Nine calculators so far: compound interest, debt payoff, savings goal, FIRE number, car loan, mortgage payoff, 401(k) projection, rent vs. buy, and net worth tracker. Everything runs client-side in vanilla JS and no frameworks, no server calls. I wanted it to load instantly and work without an internet connection after the first load. Each page has a "how the math works" section with the actual formula so you can verify it isn't doing something wrong. Would especially appreciate feedback on the FIRE and rent vs. buy calculators as those have the most opinionated assumptions (4% SWR, 7% real return) and I'd rather find out they're wrong here than in a comment on another board six months from now.

MoneyCal

Free finance calculators. Simple, no signup, no fluff

Free finance calculators. Simple, no signup, no fluff