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Percent Difference Calculator

Calculate the symmetric percent difference between two values.

Introduction

Percent Difference Calculator — Calculate the symmetric percent difference between two values. Enter Value A, Value B to get an instant, accurate result.

Formula

Percent difference = (|a − b| / ((|a| + |b|) / 2)) × 100 — the absolute difference relative to the average of the two values, used when neither value is clearly the "original" (unlike percent change).

Step-by-step

  1. Enter the Value A.
  2. Enter the Value B.
  3. Click Calculate to see your result instantly.

Real-world example

Example: With Value A = 10, Value B = 20, the Percent Difference Calculator gives Percent Difference: 66.6667.

Frequently Asked Questions

How is this different from percent change?
Percent change measures growth relative to a specific original value; percent difference is symmetric and measures the gap relative to the average of both values, useful when neither is a clear starting point.
What if both values are 0?
The average is 0, so percent difference is undefined and no result is returned.
What inputs does the Percent Difference Calculator need?
You'll need to provide: Value A, Value B. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Percent Difference Calculator?
The Percent Difference Calculator applies the formula exactly as calculated — Percent difference = (|a − b| / ((|a| + |b|) / 2)) × 100 — the absolute difference relative to the average of the two values, used when neither value is clearly the "original" (unlike percent change). — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Percent Difference Calculator free to use?
Yes, the Percent Difference Calculator is completely free, requires no signup, and runs instantly in your browser.

About the Percent Difference Calculator

The Percent Difference Calculator uses a real, verifiable formula — Percent difference = (|a − b| / ((|a| + |b|) / 2)) × 100 — the absolute difference relative to the average of the two values, used when neither value is clearly the "original" (unlike percent change). — so results are accurate every time, not an approximation.