Pick the question you need answered and type your numbers. The answer and the formula update as you type.
How percentages work
“Percent” means “per hundred”, so 15% is 15 out of every 100. Almost every percentage question is one of the three this calculator handles.
Examples
Common questions
How do I calculate a percentage of a number?
Divide the percentage by 100, then multiply by the number. For example, 15% of 80 is (15 ÷ 100) × 80 = 12.
How do I find what percent one number is of another?
Divide the part by the total, then multiply by 100. For example, 12 out of 80 is (12 ÷ 80) × 100 = 15%.
How do I calculate percent increase or decrease?
Subtract the old value from the new value, divide by the old value, then multiply by 100. Going from 80 to 100 is ((100 − 80) ÷ 80) × 100 = a 25% increase.
Why is a 50% increase followed by a 50% decrease not the same number?
Because each percentage is based on a different starting value. 100 up 50% is 150, but 150 down 50% is 75, not 100.