Make Smarter Financial Decisions With Better Calculators

Free financial calculators for loans, mortgages, investments, savings, debt, retirement and everyday money decisions — each one with charts, full schedules, worked examples and documented formulas.

Most used calculators

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What are you trying to do?

Decision & comparison tools

The most useful answers are comparisons: this loan or that one, extra payments or not, rent or buy. These tools put both options side by side.

Trust & methodology

Numbers you can check

A calculator is only useful if you can trust it — so nothing here is a black box. Every calculator documents exactly how it works, and the full methodology is public.

How our calculations work
  • Every formula shown on the page, with variables explained
  • Automated tests verify results against known reference values
  • Assumptions and limitations stated on every calculator
  • Estimates for education — never personalized financial advice
  • Runs in your browser: your numbers are never sent to a server

Finance, explained properly

All guides

About Finance Calculator X

Finance Calculator X is an independent collection of financial calculators for the decisions most people actually face: borrowing, buying a home, saving, investing and paying off debt. Each calculator is built as a complete decision-support tool — a large, clear answer, the supporting numbers behind it, an interactive chart, a full schedule you can export, and a plain-English explanation of the mathematics involved. Calculations run instantly in your browser and are documented and tested. The site is free to use and no account is ever required. More about the project →