Question 1

How do I calculate a percentage increase?

Accepted Answer

Use the Change from A to B box: it divides the difference by the original value. Going from 200 to 250 is a 25% increase; going from 250 back to 200 is a 20% decrease, because the base value changed.

Question 2

Which units can I convert?

Accepted Answer

Length, weight, area, volume, speed and data size, plus temperature between Celsius, Fahrenheit and Kelvin. Temperature is handled separately because it needs an offset, not just a multiplier.

Question 3

Does the calculator work offline?

Accepted Answer

Yes. Once the page has loaded, every calculation happens in your browser with no network requests, so it keeps working on a plane or in a basement.