Calculators for real decisions
People use calculators before decisions that matter: whether a mortgage payment fits a budget, how much a savings plan will grow, what an hourly rate means as a yearly salary, when a baby is due, or how many days are left before a deadline. The calculators here are built for those moments, with sensible defaults so you see a meaningful result immediately and change only the numbers that are yours.
They are grouped into finance, health, dates and time, school, and math and units.
How results are calculated
Every calculator shows the formula it uses and explains its assumptions, such as whether interest compounds monthly or daily, or which BMI categories apply. Finance calculators produce full schedules you can export, so you can check any month yourself. Results are estimates for planning: lenders, doctors and schools may use slightly different rules, and the pages say where that is likely.
Numbers and dates follow the format of your device's language, and money calculators work in any currency.
Shareable and private
Your inputs never leave your device; the arithmetic runs in the page. Where it is useful, the current inputs are kept in the page address so you can bookmark a calculation or send it to someone, and they will see the same numbers. Nothing is stored on a server and you don't need an account.
Using the results well
Treat the results as a starting point for a conversation with a lender, doctor or school rather than a final answer, and check the assumptions panel when a number looks surprising. Small inputs matter: a quarter of a percentage point on a 30-year loan, or an extra hour a week in a salary conversion, changes the result more than people expect. Every calculator keeps working offline once the page has loaded.