Percentage Calculator
Four percentage calculators in one: percent of a number, what percent X is of Y, percentage change, and increasing or decreasing a number by a percentage. Results update as you type, with the formula shown.
Runs entirely in your browser.
Calculate Percentages Online
What is X% of Y?
X is what percent of Y?
Percentage change from X to Y
Increase / decrease Y by X%
Decreased: 68
About Percentages
A percentage is a fraction with 100 as the denominator: 25% means 25 out of every 100, or 0.25 as a decimal. That single idea covers all four calculators on this page. Taking X% of a number means multiplying by X÷100; asking what percent X is of Y means dividing X by Y and multiplying by 100.
Percentage change compares a new value to an original value: (new − old) ÷ old × 100. The original value is always the reference, which is why a change from 50 to 100 is +100% while the reverse, from 100 to 50, is only −50%. This asymmetry trips many people up - an X% drop is never undone by an X% rise.
Each result on this page shows the formula written out with your numbers, so you can follow the math and reproduce it by hand or in code. All calculations run in your browser.
