Percentages
Percentage difference calculator
Find the percentage difference between two values when neither is the starting value. The order of the numbers does not affect the answer.
How to calculate it
Percentage difference compares two non-negative numbers against their average. For 80 and 100, the absolute gap is 20 and their average is 90, so the difference is 20 ÷ 90 × 100 = 22.22%. This is useful for comparing two quotes or measurements without treating either as the original. If one number is the original and the other is a later value, use percentage change instead.
Worked examples
| Example | Working | Answer |
|---|---|---|
| 80 and 100 | 20 ÷ 90 × 100 | 22.22% |
| 100 and 80 | 20 ÷ 90 × 100 | 22.22% |
| 4 and 6 | 2 ÷ 5 × 100 | 40% |
| 50 and 50 | 0 ÷ 50 × 100 | 0% |
| 0 and 10 | 10 ÷ 5 × 100 | 200% |
| 90 and 110 | 20 ÷ 100 × 100 | 20% |
Frequently asked questions
What is the difference between percentage difference and percentage change?
Percentage difference uses the average of both values as the baseline and has no direction. Percentage change uses the original value and can be an increase or decrease. For 80 and 100, the difference is about 22.22%, while the change from 80 to 100 is 25%.
Does swapping the values change the result?
No. The absolute gap and average stay the same, so the percentage difference is symmetric.
Can I compare zero with another number?
Yes. Zero and any positive number have a percentage difference of 200% under this formula. Two zeros have an average of zero, so the result is undefined.
Why are negative numbers excluded?
With negative inputs, the average can be zero or negative and the usual percentage difference interpretation becomes unclear. This tool is for non-negative quantities such as prices and measurements.
Can the result exceed 100%?
Yes. The greatest result for non-negative values is 200%, reached when one value is zero and the other is positive.
Method: standard arithmetic. Examples are illustrative. How our calculators work.