How to use Percentage calculator
- Find the calculator that matches your question.
- Type the two numbers.
- Read the answer underneath.
Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. 20% of 150 is 150 × 20 ÷ 100 = 30.
How do I calculate percentage change?
Subtract the old value from the new one, divide by the old value and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 × 100 = 25% increase.
How do I work out what percent X is of Y?
Divide X by Y and multiply by 100. 30 of 120 is 30 ÷ 120 × 100 = 25%.
Last updated 13 November 2026.