Free Online Calculators
All Calculators
How these calculators work
There are 4 calculators here so far, and they all behave the same way. Results update as you type, there is no Calculate button to hunt for, and nothing is hidden behind a sign-up.
The formula is on the page
Not a black box that returns a number. Each page shows the formula it uses, states the assumptions it makes, and works one example through with real figures so you can check the method against your own arithmetic.
You get the whole schedule
A payment on its own hides where the money goes. Every loan calculator opens the full month-by-month schedule, yearly or monthly, with the interest and principal split out and a running balance that reaches zero.
Downloads that actually open
PDF, Excel, CSV and a shareable image, generated in your browser. The spreadsheet arrives with real number, date and percent cells rather than text, so you can carry on working in it.
20 currencies, no exchange rates
Pick your currency and the symbol and number format follow it everywhere, including the exports. Lakh grouping for rupees, no decimals for yen. The figures never change: this is formatting, not conversion.
Nothing leaves your device
Every calculation runs in the browser. The numbers you type, the schedule and the files you download never reach us, which is also why we cannot show you a past calculation.
Sources you can check
Formulas come from primary sources, quoted and linked: the CDC and WHO for health bands, the standard annuity formula for loans. Each one carries unit tests, and the exports are verified by opening the files and reading them back.
Picking the right one
If you are borrowing, start from what the money is for. Buying a house is the mortgage calculator, because the payment is only part of the cost once tax, insurance, HOA dues and PMI are in it. Buying a car is the auto loan calculator, where sales tax, fees, a trade-in and a rebate all move the amount you actually finance. Anything else fixed-rate is the loan calculator, which also runs backwards: tell it the payment you can manage and it tells you the loan that payment carries.
For health, the BMI calculator gives you the number, the CDC band it falls in, and the weight range that would put your height in the healthy band, which is usually the more useful half of the answer.
Not sure what it is called? The search box above matches on what a calculator does, not just its name, and the category pages (Finance, Health) lay out what each one includes and where its formulas come from.