Percentage Calculator
Work out percentages four ways: a percentage of a number, what percent one number is of another, the change between two values, and a number increased or decreased by a percentage.
Runs in your browser. Nothing you enter is uploaded.
01How to use the Percentage Calculator
- 01Find the row that matches your question.
- 02Type your numbers into that row. Decimals, negatives and thousands separators are accepted.
- 03The answer updates as you type. Press Copy to put it on your clipboard.
02Percentage formulas
X% of Y = (X ÷ 100) × Y X as a % of Y = (X ÷ Y) × 100 % change = (New − Old) ÷ |Old| × 100 Y increased by X% = Y × (1 + X ÷ 100) Y decreased by X% = Y × (1 − X ÷ 100)
03Examples
15% of 80 is 12.
18 is 22.5% of 80.
A price moving from 40 to 50 is a 25% increase. Moving back from 50 to 40 is a 20% decrease.
200 increased by 7.5% is 215; decreased by 7.5% it is 185.
04Frequently asked questions
Why is 40 → 50 a 25% increase but 50 → 40 only a 20% decrease?
Percentage change is measured against the starting value. The difference of 10 is 25% of 40 but 20% of 50.
Can I use negative numbers?
Yes. For percentage change the calculator divides by the absolute value of the starting number, so a move from −50 to −25 is shown as a 50% increase.
How many decimal places are shown?
Up to six. Calculations use full precision and are rounded only for display.