Percentage Calculator

How to use Percentage Calculator

Enter A and B to calculate a proportion, B percent of A, or the change from A to B. Change uses the absolute starting value as its denominator. Division by zero is undefined.

Choose the question before entering numbers

A as a percentage of B uses A ÷ B × 100: A=80 and B=100 gives 80%. B percent of A uses A × B ÷ 100: A=80 and B=15 gives 12. The second mode returns an amount, not a percentage.

Calculate change from the original value

For Percentage change from A to B, enter the old value as A and the new value as B. From 80 to 100 the increase is 25%; from 100 to 80 the decrease is 20%. The different base explains why the percentages are not equal. This implementation divides the change by the absolute value of A when A is negative.

Separate percent from percentage points

A rate rising from 10% to 12% increases by two percentage points but by 20% relative to its original value. Enter 10 and 12 in change mode for the relative result. A zero base has no defined percentage change; the tool reports division by zero rather than inventing a value.

Do you upload my data?

This tool runs in your browser. Inputs and results are not sent to our server. Closing or refreshing the page clears your work, so save any results you need.

Step-by-step guide

Percentage change or percentage points? Choose the right calculation →