How to use this calculator

Percentage change compares the difference with the magnitude of the starting value.

The method

Percentage change = (new − old) / |old| × 100

Enter your values in the labeled fields and choose Calculate. The result panel shows the answer and supporting values when useful.

WORKED EXAMPLE INPUT

Old value: 80, New value: 100

Select Calculate to evaluate these example values.

Scope and limitations

The old value cannot be zero. A negative result indicates a decrease. Uses real-number arithmetic and rounds display values without changing the entered inputs. Check important results independently.

Common questions

Can I use different units?

Use consistent units unless this page is a unit converter. The result follows the units implied by the inputs.

Are results exact?

Displayed values may be rounded. Keep extra precision for important follow-up calculations.

Methods & verification

Formulas use standard mathematical definitions and fixed unit factors where applicable. See our methodology for numerical conventions, rounding, privacy, and limitations.