Percentage Calculator
What is X% of Y, percentage change, and “X is what % of Y”.
Three percentage problems, one tool
This calculator solves the three most common cases: (1) X% of Y = Y × X/100. (2) X is what percent of Y = (X/Y) × 100. (3) Percentage change from A to B = (B−A)/A × 100. Fill in the mode you need and the answer appears instantly.
Quick mental checks
10% of any number is the number with the decimal moved one place left; 5% is half of that; 1% is two places left. These anchors make it easy to sanity-check results.
Frequently asked questions
How do I calculate a percentage increase?
Subtract the old value from the new value, divide by the old value, then multiply by 100. A price going from 80 to 92 is a 15% increase.
Why is percentage change asymmetric?
A 50% drop needs a 100% gain to recover, because the base changes. Always note which value is the base.