Percentage Calculator
Four percentage questions, each with its own form: a share of a number, one number as a share of another, and the change.
Result
—
Files are processed in your browser and are never uploaded to a server.
How to use
Free to use with no sign-up, no install and no usage limit.
Pick the question first. Lumping all four into one row of boxes is what makes percentage calculators confusing: "15% of 20" and "3 is what percent of 20" use the same numbers and give different answers.
The change tab divides by the absolute value of the starting number, so going from -100 to -50 reads as a 50% increase rather than a decrease. Getting the sign right matters when the baseline is negative.
A starting value of zero has no percentage change. Nothing grows from zero by a percentage, so the tool says there is no answer instead of returning 0% — a number that would read as "unchanged".
The last tab applies a percentage to a value, which covers adding tax, taking a discount and marking something up. A negative percentage subtracts.
Thousands separators and surrounding spaces are accepted, so you can paste a figure straight from a spreadsheet.
Nothing you type is sent to a server. Everything is calculated inside your browser.