Percentage Difference Calculator

What is Percentage Difference?

Percentage difference is used when you want to compare two numbers that represent the same type of thing, but neither number is the obvious “original” or “starting” value.

For example, if you are comparing the height of two trees, or the population of two different cities, there is no chronological order. You just want to know how different they are from each other relative to their average size.

Because the order doesn’t matter, a percentage difference is always a positive number (an absolute value).

The Percentage Difference Formula

To calculate the percentage difference manually, you need to find the absolute difference between the two numbers, and divide that by the average of the two numbers. Finally, multiply by 100.

Percentage Difference =
[ |V1 – V2| / ((V1 + V2) / 2) ] × 100

Step-by-Step Example

Let’s say City A has a population of 500,000 and City B has a population of 600,000. What is the percentage difference between their populations?

Find the absolute difference: |500,000 - 600,000| = 100,000
Find the average of the two numbers: (500,000 + 600,000) / 2 = 550,000
Divide the difference by the average: 100,000 / 550,000 ≈ 0.1818
Multiply by 100: 0.1818 × 100 = 18.18%

The populations have an 18.18% Difference.

Percentage Difference vs. Percentage Change

It is incredibly common to confuse these two concepts. Here is the easiest way to remember which calculator to use:

Difference

Comparing two distinct, independent items at the same time.

Comparing prices of shoes at Nike vs Adidas.
Comparing heights of two siblings.
Order does NOT matter.

Change

Comparing the same item at two different points in time.

Your salary from 2022 vs 2023.
Bitcoin’s price yesterday vs today.
Order DOES matter (Old vs New).

Use Change Calculator →

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Frequently Asked Questions

How to calculate a percent difference between two numbers?

To calculate the percentage difference, find the absolute difference between the two numbers, divide it by their average, and multiply by 100. The formula is: (|Value 1 – Value 2| / ((Value 1 + Value 2) / 2)) × 100.

When should I use percentage difference instead of percentage change?

Use percentage difference when comparing two separate things at the same time where neither is the ‘original’ value (e.g., comparing the population of two different cities). Use percentage change when tracking one thing over time (e.g., your salary from last year to this year).

Can a percentage difference be negative?

No. Because the formula uses the absolute difference (ignoring negative signs), a percentage difference is always expressed as a positive number or zero.

Calculate Difference