This percentage-change calculator measures how much a value rose or fell relative to its starting point.
Math
Percentage Change Calculator
Calculate percentage increase or decrease between two values.
Calculator
About this calculator
Formula notes
Percentage change = (new - old) / old x 100.
Worked examples
- Example: a change from 80 to 100 is a 25% increase because (100 - 80) / 80 x 100 = 25.
- A value falling from 80 to 60 changes by -20, and percentage change is -20 / 80 x 100 = -25%.
How to use it
- Enter the original value and the new value.
- Review whether the result is an increase or a decrease.
- Use the signed percentage in reports or comparisons.
Frequently asked questions
What if the original value is zero?
Percentage change cannot be calculated when the original value is zero, because dividing by zero is impossible in standard arithmetic.
Why does a 50% fall need a 100% rise to recover?
After a fall from 100 to 50, the recovery is measured from the new baseline of 50; gaining 50 is therefore 100%.
Limits and interpretation
- The original value is the denominator, so reversing old and new values produces a different percentage.
- Percentage change from an original value of zero is undefined; use an absolute change or another baseline instead.