Zerdly

Percentage Difference Calculator

Find the percentage difference or percent change between two numbers with this free calculator that works instantly right in your browser.

100% FreeRuns in your browserBasic
How to use this calculator

Enter Values

Enter your values and press Calculate to see results.

Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.

How to use this calculator

  1. Enter the two values.
  2. Press Calculate.

How it works

Percentage difference = |a − b| ÷ the average of a and b × 100 — a symmetric comparison.

Worked example

80 and 100. ≈ 22.2%.

Common mistakes

  • Confusing percentage difference with percentage change — difference uses the average of the two values as the base.
  • Expecting a sign — percentage difference is always positive.

Frequently asked questions

Percentage difference vs percentage change?

Difference compares two values symmetrically (using their average as the base); change measures from an original value to a new one.

Is percentage difference always positive?

Yes — it uses the absolute difference, so the order of the two values doesn't matter.

How is this different from percentage change?

Percentage difference is symmetric — it compares two values against their average, with no 'from' or 'to'. Percentage change has a clear direction (old → new).

Related tools

Explore more in Maths, Education & Science.

Cite this tool

Zerdly. (2026). Percentage Difference Calculator. Retrieved from https://www.zerdly.com/tools/percentage-difference-calculator/

Tip: Enter any known values to calculate the remaining results.

All calculations run in your browser. Your inputs are never saved or transmitted.