The concept
What percentage change measures
Percentage change expresses a difference relative to the starting value. It makes changes in differently sized quantities easier to compare.
The original value is the denominator. If it is zero, percentage change is undefined even though an absolute difference can still be calculated.
The method
How the calculation works
The original value is subtracted from the new value. That difference is divided by the absolute original value and multiplied by 100.
The difference is divided by the absolute original value, preserving the direction of the change.
Worked example
A neutral example
A change from 200 to 250 is an absolute increase of 50 and a percentage increase of 25%. Reversing the values produces a different percentage because the base changes.
This example explains the method. It does not recommend a financial action or predict an outcome.
Frequently asked
Percentage Change Calculator questions
Why is change from zero undefined?+
Division by zero is undefined, so no finite percentage can be produced.
Can the result be negative?+
Yes. A negative result represents a decrease from the original value.
Is percentage change the same as percentage-point change?+
No. Percentage points compare two percentages directly; percentage change measures their relative difference.