Percentage Change Calculator

Worked example

100 to 120 — 20% increase

Quick answer

What does a negative result mean?

A negative percentage change means the new value is lower than the old value.

What is the Percentage Change Calculator?

Measure the percentage increase or decrease from an old value to a new value. Use it when you have the required inputs and want a deterministic, repeatable result with the calculation method visible.

How to use this calculator

Enter the values requested by the tool, keep units and time periods consistent, resolve any validation message, calculate, then review the primary answer together with the displayed formula and supporting values.

Formula and method

This calculator uses a deterministic formula and shows the calculation breakdown with the result so the answer can be checked.

Worked example

100 to 120 20% increase

Common mistakes to avoid

Check units, decimal points, percentages, signs, date/time order, selector choices, and rounding. For important decisions, verify the result against an independent source or qualified professional when appropriate.