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.
Percentage change formula
Subtract the original value from the new value, divide by the original value and multiply by 100. A positive result is an increase and a negative result is a decrease.
Worked examples
From 50 to 65 is a 30% increase. From 200 to 150 is a 25% decrease. From 80 to 100 is a 25% increase.
Percentage change versus percentage points
If an interest rate moves from 4% to 5%, that is a rise of 1 percentage point, but a 25% increase in the rate itself.
Frequently asked questions
How do I calculate a percentage increase?
(New − original) ÷ original × 100. For example, from £40 to £50 is (10 ÷ 40) × 100 = 25%.
How do I calculate a percentage decrease?
Use the same formula. The result will be negative: from £50 to £40 is −20%.
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.