Percentage Calculator
The three percentage questions, answered instantly: what is X% of Y, X is what percent of Y, and the percentage change between two numbers.
What do you want to work out?
%
What is X% of Y?
30
20% of 150 is 30.
Frequently asked questions
How do I work out X% of a number?
Divide the percentage by 100 and multiply: 20% of 150 = (20 ÷ 100) × 150 = 30. A handy shortcut: 10% is the number divided by 10, and you can build most percentages from there (20% = 2 × 10%, 5% = half of 10%).
How do I work out what percentage one number is of another?
Divide the part by the whole and multiply by 100: 30 out of 150 = (30 ÷ 150) × 100 = 20%. This is the calculation behind test scores, discounts, and market shares.
How is percentage change calculated?
Subtract the old value from the new, divide by the old value, and multiply by 100: from 100 to 125 = (125 − 100) ÷ 100 × 100 = +25%. Note the asymmetry: a 25% rise followed by a 25% fall does not return to the start.