Work out a percentage increase in seconds
A percentage increase calculator shows how much a value has grown compared with where it started. Enter the old value and the new value, and the tool gives you the increase amount and the percentage increase, with the formula shown so you can check the working. It is ideal for prices, pay, savings, sales, exam marks, website visitors and any other figure that changes over time.
Percentages are easier to compare than raw amounts. A rise of 20 sounds small on a salary of 2,000, but large on a weekly shop of 80. Turning the change into a percentage puts both rises on the same scale. This free calculator works in your browser on any device, needs no sign-up, and gives an instant answer.
Percentage Increase Calculator
How to use the percentage increase calculator
- Enter the starting figure in the Old value box. This is the value before the change.
- Enter the later figure in the New value box. This is the value after the change.
- Press Calculate. The tool subtracts the old value from the new value, then divides by the old value and multiplies by 100.
- Read the result. If the new value is higher, you will see a percentage increase. If it is lower, the tool clearly labels the result as a percentage decrease instead.
- Change either figure and calculate again to compare a different rise or fall.
Enter both figures in the same units, for example both in pounds, both in kilograms or both as a count of visitors. Mixing units will give a misleading percentage, even though the maths will still run.
Worked examples
First example: a price rises from 80 to 100. The increase is 100 minus 80, which is 20. Divide 20 by 80 to get 0.25, and multiply by 100 to get 25%. The result is therefore an increase of 20, or 25%. The formula shown by the tool is (100 - 80) / 80 x 100 = 25%.
Second example: a value rises from 50 to 75. The increase is 75 minus 50, which is 25. Divide 25 by 50 to get 0.5, and multiply by 100 to get 50%. Try 50 to 75 in the tool above and you will see an increase of 25, or 50%. A fall works the other way: if a value drops from 100 to 75, the decrease is 25, and 25 divided by 100 is 25%, so the tool reports a percentage decrease of 25%.
Tips for using percentages well
Always be clear about the starting value, because the percentage depends on it. A rise from 50 to 75 is 50%, but the same rise of 25 from 200 to 225 is only 12.5%. Do not add percentages from different starting values together, as that is a common mistake. For example, a 10% rise followed by a 10% fall does not return you to the original figure, because the fall is calculated from the higher value. If you need the new value after a percentage rise, multiply the old value by one plus the percentage as a decimal. A 25% rise on 80 is 80 times 1.25, which is 100.
Frequently asked questions
1. What is the formula for percentage increase?
Percentage increase equals the new value minus the old value, divided by the old value, multiplied by 100. In symbols, it is (New - Old) / Old x 100. The tool shows this formula with your own figures filled in.
2. What happens if the new value is lower than the old value?
The tool does not pretend it is an increase. It calculates the same difference and clearly labels the result as a percentage decrease, with the decrease amount and the percentage decrease shown. For example, 100 down to 75 is a decrease of 25, or 25%.
3. What if the old value is zero?
A percentage increase from zero cannot be calculated, because dividing by zero is not defined. The tool asks you to enter a non-zero old value in that case, so you do not get a meaningless result.
4. Can I use decimals and negative numbers?
Yes, you can enter decimals, such as 19.99 or 12.5. The tool rounds the percentage to two decimal places, so small changes remain readable. Negative values are unusual for prices and pay, so check that both figures are in the units you intend before you calculate.
5. Is a percentage increase the same as percentage points?
No. If a rate rises from 10% to 15%, that is a rise of 5 percentage points, but a 50% increase in the rate itself, because 5 divided by 10 is 50%. This calculator works out the percentage increase in a value, not the change in percentage points, unless the value you enter is itself a percentage.