How do I calculate percentage difference?

Divide the absolute gap between the two numbers by their average, then multiply by 100. Example: 40 and 60 → |40 − 60| ÷ 50 × 100 = 40%.

What is the difference between percentage difference and percentage change?

Percentage difference divides by the average of the two numbers, so it has no direction and reads the same either way round. Percentage change divides by the first value, so 40 to 60 is a 50% increase while 60 to 40 is a 33.33% decrease.

Which one should I use?

Use percentage difference when neither number came first — two measurements, two prices, two test results. Use percentage change when one number is the starting point and the other is the outcome.

Can percentage difference be negative?

No. It uses the absolute gap, so the answer is always zero or positive. If you need a direction, use percentage change instead.

Can percentage difference be over 100%?

Yes, when one number is more than three times the other. For example 10 and 50 differ by 40 against an average of 30, which is 133.33%.

How do I find the percentage error?

Percentage error compares the gap to the accepted value, not the average: |measured − actual| ÷ actual × 100. Use the percentage change calculator for that shape of question.

Percentage Calculator / Percentage difference calculator

Percentage Difference Calculator

Compare two numbers as a percentage when neither of them came first. The percentage change is shown beside it so you can see which answer your question actually needs.

Difference between two numbers

Percentage difference

Betweenand

40%

The same pair as a percentage change

Treating the first value as the starting point.

+50% increase

How to calculate percentage difference step by step

A worked example comparing 40 and 60. The calculator above does this instantly, but here is the arithmetic behind it.

1. Find the gap
|40 − 60| = 20
2. Find the average
(40 + 60) ÷ 2 = 50
3. Divide the gap by the average
20 ÷ 50 = 0.4
4. Multiply by 100
0.4 × 100 = 40%

Swap the two numbers and the answer stays 40% — that is the whole point of percentage difference. Percentage change would give 50% one way and 33.33% the other.

When to use percentage difference

Percentage difference is the right tool when the two numbers are peers: two shop prices for the same item, two lab measurements, two teams' results, this month against a colleague's month. It answers "how far apart are these?" without implying one came first.

Once one number is clearly the starting point — last year's revenue, the original price, the old weight — switch to percentage change, because dividing by the starting value is what makes an increase or decrease meaningful.

Common percentage difference answers

Worked out with the average-based formula. Change either number above for your own figures.

Between 40 and 6040%

Between 10 and 2066.67%

Between 20 and 3040%

Between 50 and 10066.67%

Between 100 and 12018.18%

Between 100 and 15040%

Between 25 and 75100%

Between 10 and 50133.33%

Between 5 and 618.18%

Between 1,000 and 1,1009.52%

Between 7 and 70%

Between 2 and 8120%

Percentage difference questions people ask

How do I calculate percentage difference?: Divide the absolute gap between the two numbers by their average, then multiply by 100. Example: 40 and 60 → |40 − 60| ÷ 50 × 100 = 40%.
What is the difference between percentage difference and percentage change?: Percentage difference divides by the average of the two numbers, so it has no direction and reads the same either way round. Percentage change divides by the first value, so 40 to 60 is a 50% increase while 60 to 40 is a 33.33% decrease.
Which one should I use?: Use percentage difference when neither number came first — two measurements, two prices, two test results. Use percentage change when one number is the starting point and the other is the outcome.
Can percentage difference be negative?: No. It uses the absolute gap, so the answer is always zero or positive. If you need a direction, use percentage change instead.
Can percentage difference be over 100%?: Yes, when one number is more than three times the other. For example 10 and 50 differ by 40 against an average of 30, which is 133.33%.
How do I find the percentage error?: Percentage error compares the gap to the accepted value, not the average: |measured − actual| ÷ actual × 100. Use the percentage change calculator for that shape of question.

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