Math & Scientific
Percentage Difference Calculator
Percentage Difference: it computes percent difference = |a − b| ÷ ((a + b) ÷ 2) × 100. Worked through below with real figures, and the calculator repeats the working on your own inputs — free, on-device, instant.
Percentage Difference Calculator turns your value A and value B into the answer using the percentage relationship. The maths runs locally, so nothing you enter leaves the page.
About this calculator
Percentage Difference is easiest to get wrong in the setup, not the arithmetic. It computes percent difference = |a − b| ÷ ((a + b) ÷ 2) × 100. It matters when you need the exact relationship checked quickly rather than worked through by hand. The worked example on this page (The percentage difference between 40 and 60 uses their average as the base: |40 − 60| ÷ ((40 + 60) ÷ 2) × 100 = 20 ÷ 50 × 100 = 40% .) shows the full substitution; the calculator above runs the same working on your own numbers, in your browser, with nothing uploaded.
How to use
- Enter the two values to compare.
- Press Calculate to run the percentage difference calculator.
- Read the result: the percentage difference between them.
- Press Reset to clear the percentage difference calculator and start again.
Why use Percentage Difference Calculator
Fast
Calculations run in your browser. No round trip to a server.
Private
Your inputs never leave your device. Nothing is uploaded.
Free
No signup, no paywall, no ads-in-results, no watermarks.
Accurate
Based on standard, well-established formulas.
Mobile-ready
Optimised for phones, tablets, and desktops alike.
Transparent
Honest disclaimers wherever browser limits or regional rules apply.
Common uses
Use it when preparing worksheets
Use it for science-fair and project numbers
Percentage Difference in tutoring and teaching sessions
Use it when revising for exams
Percentage Difference in statistics and data coursework
Percentage Difference in competitive-exam practice
Technical notes
Percentage Difference Calculator computes percent difference = |a − b| ÷ ((a + b) ÷ 2) × 100.
Inputs are taken exactly as entered, so check for typos before trusting an answer.
Results are rounded for display; the underlying calculation keeps full precision.
Worked example
The percentage difference between 40 and 60 uses their average as the base: |40 − 60| ÷ ((40 + 60) ÷ 2) × 100 = 20 ÷ 50 × 100 = 40%. Unlike percentage change, neither value is treated as the 'original', so the order does not matter.
FAQ
How is percentage difference calculated?
As |a − b| divided by the average of a and b, times 100.
How is it different from percent change?
Percentage difference compares two values symmetrically (order doesn't matter); percent change is relative to a starting value.
What do I enter in the Percentage Difference Calculator?
The two values you want to compare.
Does the Percentage Difference Calculator send my data to a server?
No — the Percentage Difference Calculator runs entirely in your browser, so the numbers you enter never leave your device.