What is percentage change?
Percentage change measures the size of a change relative to the original value. A positive result is an increase and a negative result is a decrease.
Percentage increase example
If a price rises from 80 to 100, the change is 20. Divide 20 by the original value of 80 and multiply by 100 to get a 25% increase.
Percentage decrease example
If a value falls from 100 to 80, the change is −20. Dividing by the original 100 gives −20%, or a 20% decrease.
Why the starting value matters
Changing from 80 to 100 is a 25% increase, but returning from 100 to 80 is a 20% decrease. The same absolute difference produces different percentages because each calculation uses a different baseline.
When to use percentage change
Use it for changes over time, such as prices, sales, populations, measurements and account balances. If neither value is a starting value, use the percentage difference calculator instead.