Percentage Change Calculator

Formula

Percent change = ((new − original) ÷ original) × 100

The change is measured relative to the starting value. A positive result is an increase; a negative result is a decrease. The calculator also reports the absolute difference between the two numbers.

Worked example

A value that rises from 100 to 125 is a 25% increase — the absolute change is 25, and the formula is ((125 − 100) ÷ 100) × 100.

Where this can give the wrong answer

• The original value (from) cannot be zero — percentage change is undefined when you divide by zero, so the calculator returns an error instead of showing Infinity.
• A drop from 100 to 75 is a 25% decrease, but a rise from 75 back to 100 is a 33.33% increase — the direction matters because each percentage is relative to its own starting point.
• Negative starting or ending values are accepted (e.g. from −50 to −25), which is useful for losses or temperatures, but the sign of the result can be harder to interpret than with all-positive numbers.

Related calculators

• Percentage Calculator
• ROI Calculator