Percentage Difference Calculator.
Use this calculator to quickly and accurately find the percentage difference between two numbers. Enter any two values to calculate how different they are as a percentage, using the standard percentage difference formula.
This calculator is ideal when comparing two values where neither is considered the “original” value.
Use this percentage difference calculator to find the percentage difference between two values. Enter two numbers and the calculator will show the percentage difference and the step-by-step method.
Percentage Difference Calculator
Use percentage difference when comparing two values with no clear “start” value. Use percentage change when A is the original value and B is the new value.
Percentage difference
—
—
Absolute difference
—
|A − B|
Average of values
—
(A + B) / 2
Show calculation steps
What Is Percentage Difference?
The percentage difference measures how far apart two values are relative to their average. Unlike percentage change, it treats both values equally and does not assume that one value precedes the other.
This makes the percentage difference useful for comparisons in maths, science, finance, pricing, and data analysis.
Percentage Difference Formula
The formula for percentage difference is:
Percentage difference = |A − B| ÷ ((|A| + |B|) ÷ 2) × 100
Where:
A and B are the two values being compared.
| | means absolute value
This calculator applies the formula automatically and shows the calculation steps.
How the Percentage Difference Calculator Works
This calculator follows three steps:
Calculates the absolute difference between the two values
Calculates the average of the two values
Divides the difference by the average and multiplies by 100
The result is the percentage difference between the two numbers.
Percentage Difference vs Percentage Change
It’s important to understand the difference:
Percentage Difference
No starting value
Symmetrical comparison
Uses the average of both values
Percentage Change
Has a clear starting value
Measures increase or decrease from A to B
Uses A as the base value
This calculator allows you to switch between percentage difference and percentage change to suit your calculation.
Example Percentage Difference Calculation
If you compare 50 and 65:
Absolute difference = |50 − 65| = 15
Average = (50 + 65) ÷ 2 = 57.5
Percentage difference = (15 ÷ 57.5) × 100 = 26.09%
The calculator performs this calculation instantly.
When Should You Use Percentage Difference?
Use percentage difference when:
Comparing two values without a reference point
Analysing data sets
Comparing prices, measurements, or results
Solving maths or science problems
It’s commonly used in education, statistics, and research.
Can Percentage Difference Be Over 100%?
Yes. Percentage difference can exceed 100% if the absolute difference between the two values is greater than their average.
This is normal and depends on the size of the numbers being compared.
Common Mistakes to Avoid
Using percentage change when no starting value exists
Forgetting to divide by the average of both values
Confusing absolute difference with percentage difference
This calculator helps avoid these errors.
Summary of Percentage Difference Calculator
This percentage difference calculator provides a fast and reliable way to compare two numbers as a percentage. It includes clear results, step-by-step calculations, and a percentage change option when a starting value is required.