Percent Change Calculator

A positive result is an increase; a negative result is a decrease. For negative originals, the denominator is the original magnitude.

Percent change

Percent change
25%
Δ%=b−a∣a∣×100\Delta\% = \frac{b-a}{|a|}\times 100

How it works

Enter the original and new values. The calculator divides the difference by the absolute original value and multiplies by 100. A zero original has no defined relative change.

Example

A change from 100 to 125 is a 25% increase. From 100 to 80 is a 20% decrease.

Frequently asked questions

How are negative starting values handled?

The denominator uses the original magnitude. From −100 to −50 is +50% under this convention. Signed-base formulas used in some contexts may give a different sign.

Is percentage change symmetric?

No. From 100 to 125 is +25%, but from 125 to 100 is −20%, because the original value changes.