Percentage Difference Calculator

A symmetric comparison, where neither value is the reference.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

First value

Second value

Percentage difference

40.00%

100 → 150, a increase

Absolute change50

Percentage change+50.00%

Percentage difference (symmetric)40.00%

Multiplier× 1.5

Reverse needed to undo it33.33%

Percentage difference has no direction — it divides by the average of the two values rather than by one of them, so swapping the inputs gives the same answer. That makes it the right measure when neither value is the reference, and it is why it reads 40.00% where a one-directional change reads 50.00%.

How the Percentage Difference Calculator works

Percentage difference divides by the average of the two values rather than by one of them, so swapping the inputs gives the same answer. That makes it the right measure when neither value is the baseline — comparing two measurements, two suppliers, two results.

Also known as: percent difference formula · relative difference calculator · percent difference vs percent change · difference between two values as a percentage

Where to go next

The Percentage Difference question rarely arrives on its own. These are the ones that usually come with it:

Percentage Change Calculator — Change, and the reverse move needed to undo it.
Percentage Increase Calculator — How much something went up, and the multiplier behind it.
Ratio Calculator — Simplify a ratio, and see it as shares of the whole.
Percentage Calculator — Every common percentage question in one place.

Sources

NIST Digital Library of Mathematical Functions

Frequently asked questions

What is percentage difference?

The gap between two values divided by their average, as a percentage. Between 100 and 150 it is 40%, where the one-directional change would read 50%.

How is it different from percentage change?

Change has a direction and a baseline; difference has neither. Change from 100 to 150 is +50% while 150 to 100 is −33.3%, but the percentage difference is 40% either way.

When should I use percentage difference?

When neither value is 'first' — comparing two independent measurements, two competing quotes, or two lab results. If one value is genuinely a starting point, use percentage change instead.

Why divide by the average?

To make the measure symmetric. Dividing by either value alone would give a different answer depending on which you picked, which is exactly what this measure avoids.

Put this calculator on your own site

Free to use, on any site, commercial or not. Paste this where you want it to appear. It is a plain iframe, so it works in WordPress, Squarespace, Wix, Webflow, Ghost and anything else that accepts HTML.

The one-line version

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