Free · No signup · No black boxes

Financial calculators
that show their work

Every formula is visible. Every result is explained. No "just trust us" answers — see exactly why the number is what it is.

Why OpenCalc?

Shows the math

Every result breaks down exactly how it was calculated. You can verify it, challenge it, or adjust assumptions.

No email walls

Use every tool fully without creating an account or handing over your email address first.

Honest caveats

Every tool says what it doesn't model. No calculator is perfect — we tell you where to apply judgment.