Percentage Difference Calculator
Calculate the percentage difference between two numbers using the standard percent difference formula.
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Enter your values and click Calculate
How It Works
Percentage difference is calculated using the formula: |A − B| ÷ ((A + B) / 2) × 100. First, the absolute difference between the two values is found by subtracting one from the other and removing any negative sign. That difference is then divided by the average (midpoint) of the two values, which serves as a neutral reference point. Multiplying by 100 expresses the result as a percentage. Because both the numerator and denominator treat A and B symmetrically, swapping which value is A and which is B always produces the same result — a key distinction from percent change.
Examples
Comparing two prices: $40 vs $60
Finding the percentage difference between two product prices.
Result: 40% percentage difference.
Comparing measurements: 95 vs 105
Two lab measurements being compared for variance.
Result: Approximately 10% percentage difference.
Comparing two salaries: $58,000 vs $72,000
How different are two job offers in percentage terms?
Result: Approximately 21.5% percentage difference.
Frequently Asked Questions
What is the difference between percentage difference and percentage change?
Percentage change measures how much a value has changed from a starting point — it has a clear 'before' and 'after'. Percentage difference compares two values symmetrically with no defined direction. For example, going from 40 to 60 is a 50% increase, but the percentage difference between 40 and 60 is 40% (relative to their average of 50).
Why do we divide by the average instead of one of the values?
Dividing by the average ensures the result is symmetric — it doesn't matter which value is A and which is B. If you divided by A, swapping the values would give a different answer. The average acts as a neutral reference point between the two numbers.
When should I use percentage difference?
Use percentage difference when comparing two values that have equal standing — such as two competing prices, two experimental measurements, or two athletes' scores. Use percentage change instead when one value is clearly the original and the other is the new value (like a price increase over time).