Percentage Difference Between Two Numbers

The percentage difference is a useful way to measure how much two values differ in relative terms. It's commonly used in finance, science, sales analysis, and data comparison. Unlike a simple subtraction, it tells you how big the change is compared to the average of the two numbers.

Examples:

A = 100, B = 120 → Difference = 18.18%
A = 75, B = 125 → Difference = 50%

Tips:

This method compares values relative to their average, not just one of them.
Useful when there is no clear base value for increase/decrease.

Why It Matters

It shows the difference as a percentage, making comparison easier.
It’s unbiased—it treats both values equally, unlike percentage increase/decrease which starts from one number.
Ideal for comparing test results, prices, measurements, or financial figures.

Formula

The percentage difference between two numbers A and B is calculated as:

Percentage Difference = (|A − B| / Average of A and B) × 100

Where:

|A − B| is the absolute difference
Average of A and B = (A + B) / 2

Example Calculations

A = 100, B = 120 → Difference = 20, Average = 110 → % Difference = 18.18%
A = 75, B = 125 → Difference = 50, Average = 100 → % Difference = 50%
A = 0, B = 0 → % Difference = 0%

When to Use Percentage Difference

To compare two experimental results or scientific measurements.
To show how two prices vary (e.g., cost at Store A vs Store B).
To present variance between projected and actual numbers.

Common Misconceptions

It is not the same as percentage change or increase.
If you care about “growth from one number,” use percentage increase instead.
Percentage difference treats both values symmetrically.

Use our Percentage Difference Calculator to compare any two values and understand the real scale of their difference—mathematically accurate, fast, and easy.