Speedy Calculator

Speedy Calculator is a free collection of more than 3,000 online calculators across 13 categories, including finance, health, math, physics, chemistry, statistics, construction, unit conversion, cooking and sports. Every calculator shows the formula it uses, a worked example and the sources its method is based on, so you can check the answer instead of just trusting it. Key features: Work backwards: enter the result you want and the calculator solves for the missing input. Switch between metric and imperial units on any field without losing your values. Instant results with no sign-up required. Step-by-step guides on common questions, such as calculating a due date, choosing between debt snowball and avalanche, or working out how much paint a room needs.