Percentage Calculator
Four common percentage questions, each answered as you type.
How to use this tool
- Pick the box that matches your question and fill in both numbers.
- The answer appears as soon as both fields have a value.
- Use Reset in a box to clear just that calculation.
How it works
A percentage is a number out of 100. To take a percentage of a value, divide the percentage by 100 and multiply.
Percentage change compares a new value with the old one, so the starting value matters. Going from 50 to 75 is up 50%, but going from 75 back to 50 is down 33.3%.
X% of Y = X / 100 x Y
X is what percent of Y = X / Y x 100
Change = (new - old) / old x 100
Increase by P% = value x (1 + P / 100)
Example. 15% of 200 is 30. 30 is 15% of 200. Going from 50 to 75 is a 50% increase.
Frequently asked questions
Why is a rise and fall of the same percent not equal?
Each change is measured from a different starting value. Up 50% then down 50% leaves you 25% below where you began.
Can I use negative numbers?
Yes. Negative values work in all four boxes. A starting value or total of zero cannot be used where it is the divisor.
How do I work out a discount?
Use the discount calculator, which shows the final price and the amount saved together.