PercentLab

Percentage Calculator

A free percentage calculator that handles the three questions people actually search for: "what is X% of Y", "what is the percent change from A to B", and "A is what percent of B". Pick an operation, type two numbers, and the result updates instantly, rounded to two decimal places. Everything runs in your browser; nothing you enter is uploaded or stored. The math is deliberately transparent — percent of a number multiplies a/100 by the number, percent change divides the difference by the starting value, and the what-percent mode divides the part by the whole. Division by zero returns 0 instead of an error, so the tool stays usable while you are still typing.