About NumberCals

NumberCals is a free collection of online calculators designed to help with everyday math, finance, health, business, and engineering tasks. Every calculator is built around a well-known formula, with the source and reasoning explained on each page.

What we build

The site currently offers 72 calculators across eight categories — finance (mortgages, EMI, investment growth, compound interest), health (BMI, BMR, TDEE, body fat), math (statistics, quadratic equations, combinations), time and motion, physics, business, property, and sports. Each calculator runs entirely on its own — pick the one you need, enter your numbers, and get your result instantly.

How we built it

Every calculator is implemented as a small, self-contained Python module with hand-checked reference values and an automated test suite. All formulas are open and documented. We don't track which inputs you enter — calculations happen on demand and are not stored.

What we deliberately don't build

We don't provide tax calculators (income tax, sales tax, GST). Tax rules are jurisdiction-specific, change every year, and the consequences of a wrong calculation can be significant. For tax matters, please use the official calculator published by your tax authority (the IRS in the US, the ATO in Australia, the Income Tax Department in India, HMRC in the UK, and so on) or consult a qualified tax professional.

A note on accuracy

Calculators on this site give the right answer for the inputs you provide, using the formulas documented on each page. That said, results are estimates only and should not be taken as financial, medical, legal, or tax advice. For decisions with significant financial or health implications, please consult a qualified professional.

Contact

Questions, suggestions for new calculators, or bug reports? Get in touch via the contact page.