1. Find the gap
Subtract one value from the other and take the absolute value. This keeps the gap positive.
|80 − 100| = 20Two numbers. One fair comparison.
Percentage Difference Calculator
How far apart are two numbers? Enter both values to find their percentage difference using their average. See the calculation, compare more pairs in a worksheet, or copy the formula into your spreadsheet.
- Both values count equally.
- See the gap and average.
- Keep a comparison worksheet.
Percentage difference
BiznTools · bizntools.com/business-finance/percentage-difference-calculator · Average-based comparison · Nonnegative values in the same units
Percentage difference
Updates as you editEnter two values to compare.
One comparison, a clear answer
Enter two values to see their percentage difference, the gap between them and the average used in the formula.
80↔10022.22% difference
Values stay in this tab. Links never include your numbers.
Use it in Excel or Google Sheets
Put your nonnegative values in A2 and B2, enter this formula, then format the result as Percent. At least one value must be above zero.
=ABS(A2-B2)/AVERAGE(A2:B2)Understand the result
How to calculate percentage difference
Find the gap between the two values, divide it by their average, then multiply by 100. Using the average treats both values equally: swapping them gives the same percentage difference.
2. Find their average
Add the two values and divide by two. This is the reference for the comparison.
(80 + 100) ÷ 2 = 903. Turn it into a percentage
Divide the gap by the average, then multiply by 100.
20 ÷ 90 × 100 ≈ 22.22%Absolute gap: |A − B|
Average: (A + B) ÷ 2
Percentage difference: |A − B| ÷ ((A + B) ÷ 2) × 100
Make the numbers useful
Percentage difference examples
Compare two quotes: $80 and $100
The gap is $20 and their average is $90. Divide 20 by 90, then multiply by 100: about 22.22%. If you instead ask how much $100 exceeds an $80 starting price, that is a 25% increase—a different question.
- Absolute gap
- $20
- Average price
- $90
- Percentage difference
- ≈ 22.22%
Compare measurements: 5 kg and 7 kg
The gap is 2 kg and the average is 6 kg. That gives 2 ÷ 6 × 100, or about 33.33%. Keep both measurements in the same units and check that this comparison method fits your task.
- Absolute gap
- 2 kg
- Average measurement
- 6 kg
- Percentage difference
- ≈ 33.33%
A difference greater than 100%
For 6 and 90, the gap is 84 and the average is 48. The percentage difference is 175%. This is valid: with nonnegative values, the result ranges from 0% for equal positive values to 200% when one value is zero.
- Absolute gap
- 84
- Average
- 48
- Percentage difference
- 175%
Choose the right question
Percentage difference, change and error
The denominator decides what your result means. Choose it before comparing prices, measurements or performance.
| You want to know… | Use | Divide by |
|---|---|---|
| How far apart are these two values? | This percentage difference calculator | The average of both values |
| How much did it increase or decrease? | Percentage Change Calculator | The original value |
| How far is a measurement from a known reference? | Absolute percent error | The absolute reference value |
Use the same units and a meaningful zero
Convert meters and centimeters to the same unit first. Dollar amounts should refer to the same currency and pricing basis. Percentages of Celsius or Fahrenheit temperatures can mislead because zero on those scales is arbitrary. This calculator accepts nonnegative values; signed quantities need a method chosen for that specific comparison.
Using relative percent difference for measurements
This page calculates absolute relative percent difference. Some laboratory methods keep a signed difference or impose special rules near detection limits. Follow your project’s documented method; a calculator result alone does not establish that a measurement passes a quality check.
Practical answers
Percentage difference questions
What is the percentage difference between two numbers?
It is their absolute gap divided by their average, multiplied by 100. For 70 and 85, the gap is 15 and the average is 77.5, giving about 19.35%. Neither value is treated as the original.
Is percentage difference the same as percentage change?
No. Percentage change divides the signed change by a starting value. From 80 to 100, the increase is 25%. From 100 to 80, the decrease is 20%. The percentage difference between 80 and 100 is about 22.22% in either order.
Can percentage difference be more than 100%?
Yes. For 6 and 90 it is 175%. For the nonnegative values this calculator supports, 200% is the upper bound and occurs when exactly one value is zero.
What happens when one or both numbers are zero?
Zero and 10 have a gap of 10 and an average of 5, so their difference is 200%. Zero and zero have an average of zero. The percentage is undefined, even though the absolute gap is zero.
Can I use negative values?
This tool is for nonnegative quantities with a meaningful zero. Signed values can make the average zero or produce a misleading denominator. For a before-and-after signed change, use the Percentage Change Calculator and check its interpretation rules.
What does relative percent difference mean?
RPD often compares two measurements relative to their mean. Some methods retain the sign; others use an absolute difference, as this calculator does. Follow the method specified for your project, particularly for low readings or laboratory quality control.
How do I calculate percentage difference in Excel or Google Sheets?
With valid nonnegative values in A2 and B2 and at least one above zero, enter =ABS(A2-B2)/AVERAGE(A2:B2) and format the cell as Percent. Do not multiply that formula by 100 and also apply Percent formatting, or the display will be 100 times too large.
How do I compare three or more values?
The worksheet keeps separate two-value comparisons. It does not calculate one combined percentage for an entire data set. For variability across several measurements, a range, standard deviation or coefficient of variation may answer a different question.
Calculation rules & sources
- Use comparable nonnegative quantities with a meaningful zero and the same units. This ratio is unsuitable for Celsius/Fahrenheit temperatures, calendar dates, ranks or arbitrary scores.
- Inputs accept plain decimal notation up to 1 trillion and six decimal places. Negative numbers, exponent notation and commas are not accepted.
- One zero and one positive value give 200%. Two zeros have a zero gap but an undefined percentage because their average is zero.
- Exact fractions are used internally. Display precision is selectable. Approximation signs mark rounding; small nonzero results use a bound rather than displaying zero.
- The worksheet stores up to 20 snapshots in this tab, not on a server or in browser storage. CSV uses six decimal places and includes its method. Leaving or reloading clears your entries.
- Relative percent difference conventions vary. This tool always uses the absolute gap; it does not apply laboratory acceptance criteria or interpret detection limits.
EPA New England — Environmental Data Review Supplement, page 42 — Equation 2-1 describes relative percent difference using the mean. It retains sign and notes that absolute values may be used according to project needs. This calculator explicitly uses absolute difference; it does not supply regulatory thresholds.