Percentage Change Calculator
Measure how much a value increased or decreased relative to its starting point. The result is positive for increases and negative for decreases.
Absolute change20
Percentage change+25%
How this tool works
Percentage change = (new − old) ÷ |old| × 100.
Example
Moving from 80 to 100 is a 25% increase because the 20-point change is one quarter of the original 80.
Common questions
Why is the old value in the denominator?
Percentage change measures the change relative to the starting value.
What if the old value is zero?
Percentage change from zero is undefined because division by zero is not possible.