About the percentage calculator
A percentage is a fraction of 100. This calculator covers the five questions people ask most: what is X% of Y, X is what percent of Y, X is Y% of what number, how much did a value change in percent, and what is a value after a percentage increase or decrease.
Choose the tab that matches your question, fill in the two numbers and read the answer. The details show the formula that was used so you can repeat the calculation by hand.
Percentage change is measured against the starting value. Going from 50 to 75 is a 50% increase, but going back from 75 to 50 is only a 33.33% decrease, because the starting value is different.
Formula
- X% of Y = X ÷ 100 × Y
- X is what % of Y = X ÷ Y × 100
- X is Y% of what = X ÷ Y × 100
- % change = (new − old) ÷ |old| × 100
- After a change: value × (1 ± percentage ÷ 100)
Example
15% of 200 is 0.15 × 200 = 30. A jacket priced at $80 with 25% off costs 80 × 0.75 = $60.