Percentage Calculator
Choose what you want to work out — a percentage of a number, what percentage one value is of another, or the percentage change between two values — then enter your numbers for an instant answer.
Three percentage questions, one tool
The most common percentage question is 'what is X% of Y'. To find it, divide the percentage by 100 and multiply by the number — for example, 15% of 200 is 0.15 × 200 = 30.
The second is 'X is what percent of Y', found by dividing X by Y and multiplying by 100. The third is percentage change, calculated as the difference divided by the original value, times 100 — positive for an increase and negative for a decrease.
Why percentages trip people up
A common mistake is to confuse a percentage change with a percentage point change, or to calculate change against the new value instead of the original. Percentage change is always measured against the starting figure.
Another is reversing a discount: a price that has been cut by 20% is not restored by adding 20%, because the 20% is now taken from a smaller base.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 20% of 150 is 0.20 × 150 = 30.
How do I work out percentage change?
Subtract the original value from the new value, divide by the original value, then multiply by 100. A result above zero is an increase; below zero is a decrease.
What is the difference between percent and percentage points?
A move from 10% to 15% is a 5 percentage-point rise, but a 50% increase in relative terms. This tool reports relative percentage change.