About Formulopia

Formulopia is a free library of calculators for personal finance, business, unit conversion and science, used at home, at work and in class. Every calculator can be solved for any of its variables, accepts any combination of units and shows the substitution step by step.

How we keep results accurate

• Financial formulas follow standard banking conventions (monthly payments, nominal annual rate divided by 12).
• Physical constants come from CODATA 2018 and atomic weights from the IUPAC standard values.
• Every formula ships with test cases: each one is solved for every variable and checked against known textbook results before it is published.
• All calculations run in your browser. Nothing you type is sent to a server.

Found a mistake or missing a calculator? Write to hello@formulopia.com.