CalcFinch is a collection of 40 free online calculators for personal finance, health and fitness, math, conversions and dates. Our goal is simple: give you a correct answer quickly, and show you how it was calculated so you can trust it.
How we build our calculators
- Established formulas. We use standard, published methods — the amortization formula lenders use, the Mifflin-St Jeor equation for metabolism, the U.S. Navy body fat method, Naegele’s rule for due dates and so on — and name the method on every page.
- Tested against known values. Each calculator’s logic is covered by automated tests that compare results with worked examples and reference values before anything is published.
- Explained in plain language. Every page includes the formula, a worked example and answers to common questions.
- Reviewed and updated. We review content periodically and correct anything that is out of date. If you spot an error, please tell us.
Your privacy
All calculations happen in your browser. The numbers you enter are not sent to our servers or stored. See our privacy policy for details about cookies and advertising.
How the site is funded
CalcFinch is free to use and supported by advertising. Ads never influence our calculations or content.
Important note
Our calculators provide estimates for informational and educational purposes. They are not financial, medical, tax or legal advice. Please read our disclaimer.