About Calculation Machine

Calculation Machine is an independent collection of free calculators for money, maths, health, home projects and HVAC. Every tool states its formula in the open, defines each input, shows the working for your numbers and links to the sources the method comes from.

Why this site exists

Many calculator sites bury the answer under adverts and never say how the number was produced. We think a calculator should earn trust the way a good textbook does: by showing the method, citing where it came from and making the result easy to check by hand. Each page answers one question and keeps everything else out of the way.

Who maintains the calculators

The site is written and maintained by the Calculation Machine editorial team. Formulas come from recognised references — textbooks, standards bodies and government guidance — and each calculator is checked against independent worked examples before it is published and whenever a reader reports a problem. Health and money calculators give general information only; they are not a substitute for advice from a doctor, pharmacist or licensed financial professional.

How the calculators are checked

Every formula is sourced, and every calculator is tested against worked examples before it goes live. The full process is on the methodology page.

Contact

Found an error or want a calculator added? Email [email protected].