Percentage Difference Calculator
Compare two values when neither is the “original”. Get the percentage difference with the working, and switch to percentage change when there is a before and after.
- Instant results
- Step-by-step working
- Excel formula
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Percentage difference
Fill in the boxes. The answer appears as you type.
Percentage change
Fill in the boxes. The answer appears as you type.
X is what percent of Y
Fill in the boxes. The answer appears as you type.
What is percentage difference?
Percentage difference compares two values of the same kind by dividing the gap between them by their average. Because it uses the average, the answer is the same whichever value you enter first. That makes it the right choice for comparing two prices, two measurements or two groups, where neither is the natural starting point. When one value clearly comes first in time, use percentage change instead.
How to use Percentage Difference Calculator
- Enter the two values in “Percentage difference”. Order does not matter.
- Read the percentage difference, always a positive number.
- Compare it with “Percentage change” below if one value is the original.
- Open “Show working” to copy the steps and an Excel or Google Sheets formula.
Percentage difference vs percentage change
- Percentage difference = |A − B| ÷ ((A + B) ÷ 2) × 100
- 40 and 60: 20 ÷ 50 × 100 = 40%.
- Percentage change = (B − A) ÷ A × 100
- From 40 to 60 is +50%, but from 60 to 40 is −33.3%.
- Percent error = |Measured − True| ÷ True × 100
- Use when one value is a known correct value.
- Same inputs, different questions
- Pick the formula that matches what you want to say, and name it in your report.
Why use this percentage difference calculator
- Answers as you typeNo Calculate button and no page reloads. Change any number and the result updates instantly.
- Shows the workingEvery answer comes with the steps and a plain-English sentence, so you can check it or copy it into homework and reports.
- Spreadsheet formula includedCopy the matching Excel or Google Sheets formula and reuse the calculation on a whole column.
- Private and ad-free workspaceNumbers are calculated on your device. Nothing you type is sent anywhere.
Common uses
- Comparing prices. Two stores selling the same item for $40 and $60.
- Lab measurements. Agreement between two measurements of the same quantity.
- Survey groups. How far apart two regions, teams or classes are.
- Quotes and estimates. How different two contractors’ quotes are.
Need a different calculation? Try the percentage calculator, discount calculator or percentage change calculator, or generate numbers with the random number generator.
Example: two quotes for the same job
One painter quotes $1,850 and another $2,300. In “Percentage difference”, enter both: they differ by 21.7%. If the first quote was your budget, “Percentage change” from 1850 to 2300 shows the second is 24.3% over it.
What to expect from the result
Percentage difference is undefined when the average of the two values is 0, and it is not meaningful for values with opposite signs. It is not the same as percent error, which needs a known true value.
Percentage Difference Calculator questions
How do you calculate percentage difference?
Divide the absolute difference by the average of the two numbers and multiply by 100. For 40 and 60: 20 ÷ 50 × 100 = 40%.
When should I use percentage difference instead of percentage change?
Use percentage difference when neither value is the reference point, such as comparing two shops. Use percentage change when there is an old and a new value.
Does the order of the numbers matter?
No. Percentage difference uses the average, so 40 and 60 give the same 40% as 60 and 40.
Can percentage difference be more than 100%?
Yes, up to 200%. For example, 1 and 100 have a percentage difference of about 196%.
What is the Excel formula for percentage difference?
Use =ABS(A2-B2)/AVERAGE(A2,B2) and format the cell as a percentage.