About DuckDollar

DuckDollar started with a simple frustration: most free financial calculators are either too shallow to be useful or quietly trying to upsell you something. They hide the formula. They cap the free version at three uses. They require an email to see your results.

We thought that was backwards. Good financial math should be free and transparent, full stop.

What we make

A growing library of finance calculators built on the same formulas that professional tools use — but explained, not obscured. Every tool shows the formula it uses. Every result is free. No account, no trial, no paywall.

The tools cover the things people actually wonder about: how fast debt compounds, what a FIRE number really means, how much of a freelance payment the IRS will want, whether renting actually costs more than buying once you account for opportunity cost.

How we stay free

The site runs a few unobtrusive ads. We don't sell your data, because we don't collect it. Your browser never sends any of your inputs to our servers — the math runs locally, in your tab.

What we are not

DuckDollar is for education and planning, not advice. We're not licensed financial advisors. The calculators give accurate estimates based on documented formulas, but your situation has details a calculator can't know. Use the numbers to think clearly. Then talk to a professional before acting on them.

Get in touch

Want to suggest a tool, report a bug, or just say something? Use the contact page. We read everything.