How to use the percentage calculator
Choose the question you want to answer, enter the two numbers, and the result updates instantly. The calculator handles four common percentage problems.
Percentage formulas
- X% of Y:
X ÷ 100 × Y - X is what percent of Y:
X ÷ Y × 100 - Percent change:
(new − old) ÷ |old| × 100 - Percent difference:
|X − Y| ÷ ((X + Y) ÷ 2) × 100
Percent change versus percent difference
Use percent change when one value comes before the other, such as a price rising from 80 to 100. Use percent difference when neither value is the starting point, such as comparing two stores' prices.
Frequently asked questions
How do I calculate 20% of a number?
Multiply the number by 0.20. For example, 20% of 150 is 30.
How do I work out a percentage increase?
Subtract the old value from the new value, divide by the old value and multiply by 100.