Speedy Calculator is a free collection of online calculators for money, health, maths, science, construction and everyday life. Every calculator gives instant results and shows the formula behind them, so you can see exactly how an answer was reached.
Why we built Speedy Calculator
Most calculators online give you a number and nothing else. We wanted tools that explain themselves: what the inputs mean, which formula is used, a worked example you can check by hand, and sources you can read.
How our calculators are made
- Formulas come from textbooks, standards bodies, peer-reviewed studies and official guidance, and each page lists its sources.
- Every calculator is tested with worked examples before it is published.
- Results update as you type, and many calculators can work backwards from the answer you want.
- Pages are reviewed and updated when standards or guidance change.
Important note
Our calculators are for information and education. They are not a substitute for advice from a doctor, financial adviser, engineer or other qualified professional. Always check important decisions with an expert.
Get in touch
Found a mistake, or want a calculator we do not have yet? Contact us or browse all 578 calculators.