How to use this calculator
Enter the requested values, review any options that affect the calculation, and select Calculate. The main answer appears beside the form, with supporting details below it.
How the calculation works
Percentage change = (ending value − starting value) ÷ |starting value| × 100.
Example
A move from 80 to 100 is a 25% increase because the increase of 20 is one quarter of 80.
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Frequently asked questions
Why is change from zero undefined?
A percentage change needs a non-zero starting value to serve as the denominator.
How are negative starting values handled?
The formula divides by the starting value’s magnitude so the direction comes from the actual change.