About CalculatorCrew

CalculatorCrew is a free library of online calculators for school, money, dates, home projects, health and everyday maths. We started it because too many calculator sites give you a number without telling you where it came from.

How we build our calculators

• Published formulas only. Every calculator uses a standard, documented formula, and the page explains it in plain English with a worked example.
• Checked by hand. We test each calculator against worked examples and edge cases before it goes live.
• Clear limits. Where a result is an estimate, such as loan payments or calorie needs, we say so and explain what the calculator leaves out.
• Private by design. Calculations run in your browser. The numbers you type are not sent to us or stored.

Found a mistake?

If a result looks wrong or a formula needs updating, please tell us at [email protected]. We fix reported errors quickly and update the page.

Not professional advice

Our calculators are for information and education. For decisions about loans, taxes, health or legal matters, please check with a qualified professional. See our disclaimer for details.