How it works
Percentage change = (new − original) ÷ original × 100.
A worked example
A rise from 80 to 100 is a 25% increase. Returning from 100 to 80 is a 20% decrease.
What to keep in mind
The original value must be greater than zero. This tool compares non-negative quantities.
A common question
Why are increase and decrease percentages different?
Each percentage uses its own starting value as the denominator. A larger starting value makes the same change a smaller percentage.
Results use the assumptions above. Check critical measurements and dates independently.