Percentage Difference

Percentage Difference Calculator measures how far apart two positive numbers are, as a percentage of their average. Enter Value 1 and Value 2, tap Calculate, and read the result.

Why the average and not the first number? A percentage change needs a starting point, so swapping the two numbers changes the answer. This calculator divides the gap by the midpoint of the two values instead, so 10 and 20 give the same 66.66667 percent whichever one you type first.

Worked example
Value 1 is 50 and Value 2 is 75. The gap is 25 and the average is 62.5. 25 divided by 62.5 is 0.4, so the difference is 40 percent.

Where people use it
• Comparing two lab or sensor readings of the same quantity
• Checking how far apart two quotes from different suppliers are
• Seeing whether two test scores or survey averages really differ
• Measuring how much two estimates disagree before choosing one

Good to know
• Both values must be positive numbers
• If one value is a clear before-and-after baseline, a percentage change is the better measure
• The app shows the percentage only, not the absolute gap

Built for quick checks
• Light and dark theme
• 28 languages
• A More calculators link opens the full Calculator.io app with 170+ tools

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