About

percentofthis.com is a free percentage calculator. You pick one question, type two numbers, and read the answer. The page also shows the arithmetic, so you can see where the result came from.

The questions are: a tip on a bill, what is this percent of a number, what percent one number is of another, the percent change between two numbers, and a percent off a number. The tip can be split across the people sharing the bill. The math runs in the browser. The site does not keep the numbers.

It does not look up tax rates, give loan terms, or tell you whether a price is fair. It answers the arithmetic you asked.