Percentage increase calculator
Enter an old and a new value to see how much it rose or fell, in percent.
Change
Change: 25%
- Difference
- 20
- New ÷ old
- 1.25 ×
How it works
Subtract the old value from the new one, divide by the old value and multiply by 100. A positive result is an increase, a negative one a decrease.
We divide by the absolute size of the old value, so a move from −50 to −25 shows as a 50% increase rather than a confusing negative number.
The ratio new ÷ old is the growth factor: 1.25 means the value is now 125% of what it was.
Formula
% change = (new − old) ÷ |old| × 100 factor = new ÷ old
Worked example
From 80 to 100 the change is (100 − 80) ÷ 80 × 100 = 25%, a difference of 20 and a factor of 1.25. Going back from 100 to 80 is (80 − 100) ÷ 100 × 100 = −20%.
Questions people ask
Why is going up 25% and down 20% the same pair of numbers?
Each percentage is measured from its own starting point. 20 is 25% of 80 but only 20% of 100.
Can a decrease be more than 100%?
Only if the value goes below zero. A drop from 50 to −10 is a 120% decrease.
How is this different from percentage difference?
Percentage change has a direction and uses the old value as the base. Percentage difference compares two values symmetrically, using their average as the base.