Percentage Difference in Excel: Formula and Examples

To find percentage difference in Excel, divide the absolute difference between two values by their average, then format the result as a percentage. With the earlier value in A2 and the later value in B2, enter =ABS(B2-A2)/AVERAGE(A2,B2). For example, 80 and 100 give 22.22%. This symmetric calculation compares the values without treating either one as the starting point.

Percentage difference is useful for comparing two measurements, prices, totals, or other figures when neither value is automatically the baseline. If you mean how much a value rose or fell from a specific starting value, use percentage change instead; that calculation is different.

What You’ll Need

Microsoft Excel for Microsoft 365 on Windows, or another Excel edition with the standard worksheet functions used here.
Two numeric values to compare, entered in separate cells. In the examples below, A2 contains the first or earlier value and B2 contains the second or later value.
A blank cell for the result. The calculation works with positive numbers and with zero in some cases, but the usual percentage-difference interpretation assumes comparable measurements on a meaningful scale.

You do not need to install an add-in. The ABS and AVERAGE functions are standard Excel functions. The same formula works in Excel for Mac and Excel for the web; ribbon layout and keyboard shortcuts can vary slightly by platform.

Step-by-Step

Enter the two values. Put the first value in A2 and the second in B2. For a simple example, enter 80 in A2 and 100 in B2. Add clear labels above them, such as First value and Second value, so you can tell what the cells represent later. Percentage difference is symmetric, so swapping the two values will not change the result.
Select the result cell. Click C2, or another empty cell where you want the answer to appear. Keep the original values in their own cells rather than typing them directly into the formula. Cell references make it easier to check the calculation and reuse it for additional pairs of values.
Enter the percentage-difference formula. With the first value in A2 and the second value in B2, type =ABS(B2-A2)/AVERAGE(A2,B2) in C2 and press Enter. ABS makes the difference positive regardless of which value is larger. AVERAGE supplies the midpoint of the two values as the denominator. In the example, the absolute difference is 20 and the average is 90, so the calculation is 20 divided by 90, or 0.2222 as a decimal.
Format the result as a percentage. Select C2, then choose Home > Number > Percent Style on the Windows ribbon. Excel displays the decimal as a percentage: the example should show about 22% at the default precision. To show more detail, use Increase Decimal in the Number group until two decimal places appear; the example will then read 22.22%. On Mac or Excel for the web, use the Home tab’s percentage-format control if the ribbon arrangement differs. The calculation itself is unchanged.
Check that the answer makes sense. For 80 and 100, the gap is 20 and their average is 90. The quotient is approximately 0.2222, which becomes 22.22% when displayed as a percentage. The result is not 20% simply because the values differ by 20: the percentage-difference denominator is their average, not either value alone.
Apply the calculation to more rows. If each row has a pair of values, put the first set in A2:A20 and the second set in B2:B20. Enter the formula in C2 using A2 and B2, then drag the fill handle at the bottom-right corner of C2 down the column. Excel adjusts the references for each row, so the next row uses A3 and B3, then A4 and B4, and so on. Check a couple of rows manually before relying on a long list.
Choose the right comparison for your question. Use percentage difference when comparing two figures equally, such as two methods measuring the same quantity. If the question is how much a result changed from a known baseline, use percentage change instead. With the starting value in A2 and the ending value in B2, enter =(B2-A2)/A2 in C2 and format C2 as a percentage. For 80 as the start and 100 as the end, this gives 25%, because the increase of 20 is divided by the starting value of 80. A negative result indicates a decrease.

For another percentage-difference example, suppose a pair of measurements is 45 and 60. With the first number in A2 and the second in B2, use =ABS(B2-A2)/AVERAGE(A2,B2). The difference is 15, the average is 52.5, and 15 divided by 52.5 is approximately 0.2857. After percentage formatting, the result is 28.57%. This shows why the result can differ from a percentage change based on one of the values.

Common Mistakes

Using the wrong denominator. Dividing the difference by the first value calculates a relative change from that baseline, not the symmetric percentage difference described here. Decide whether the comparison is equal-sided or has a specific starting point before choosing a formula.
Forgetting ABS. A formula that subtracts one value from the other without ABS can return a negative result when the order is reversed. Percentage difference is ordinarily reported as a nonnegative size of difference; ABS keeps the direction from affecting it.
Multiplying by 100 and applying percentage formatting. Excel’s percentage format already displays a decimal as a percentage. If the formula includes multiplication by 100 and the cell is also formatted as a percentage, 0.2222 can appear as 2,222%. Use the formula as written and apply percentage formatting once.
Confusing stored values with displayed values. A cell may display 22% while storing approximately 0.2222. That is expected. Conversely, if your source values are already percentages, confirm they are stored as numeric percentages and not as text before comparing them.
Including blanks, labels, or the wrong rows. A blank cell can be treated like zero in parts of a calculation, and a copied formula may compare mismatched records. Keep each pair on the same row, and make sure both input cells contain the intended numeric values.

Tips

Use descriptive column headings such as Sample A, Sample B, and Percentage difference. This makes the formula easier to audit, especially when comparing many pairs.
Set the number of displayed decimal places to match the purpose of the report. One or two places is often readable, but keep extra precision in the underlying calculation rather than rounding the inputs first.
For a long table, convert the range to an Excel table with Insert > Table. A formula entered in a table column can fill down automatically as new rows are added. Verify the formula references and formatting after creating the table.
Keep the original values unchanged and put the result in a separate column. This preserves the information needed to review or redo the comparison.
If comparing values with different units or scales, first confirm that percentage difference is meaningful. A percentage can make a small absolute gap look large when both values are small, and it does not explain practical importance by itself.

Troubleshooting

The cell shows 0.2222 rather than 22.22%. The formula may be correct but the cell is in General or Number format. Select the result and apply Percent Style. If it shows 22% and you need more precision, increase the displayed decimal places.
The cell shows ######. This usually means the column is too narrow for the formatted value. Widen the column by dragging its right boundary, or double-click that boundary to AutoFit it.
The formula returns #DIV/0!. The average of the two inputs is zero, so Excel cannot divide by it. If both values are zero, the conventional percentage difference is undefined because there is no nonzero average to compare against. If one value is zero and the other is nonzero, the standard formula returns 200%. Decide how your report should handle zero cases and label any special convention clearly. Opposite-sign values can also average to zero, in which case this measure is not suitable.
The formula appears as text instead of calculating. Check that the cell is not formatted as Text and that the entry begins with an equals sign. Change the format to General, then re-enter the formula by selecting the cell, pressing F2, and pressing Enter. Also check that Show Formulas is not turned on; use Ctrl+` on Windows to toggle it.
The result is unexpectedly negative or unusually large. Confirm you used ABS for percentage difference, check that the two references point to the intended cells, and verify that input cells contain numbers rather than text. If you need direction of change, calculate percentage change from a clearly identified baseline instead.

Frequently Asked Questions

What is the Excel formula for percentage difference?
With the two values in A2 and B2, enter =ABS(B2-A2)/AVERAGE(A2,B2), then format the result cell as a percentage. The formula compares the gap with the average of the values.

Is percentage difference the same as percentage change?
No. Percentage difference uses the average of both values, so neither is the baseline. Percentage change divides the change by a specific starting value and can be positive or negative.

Why does Excel show a decimal instead of a percent?
The formula returns a decimal number. Select the result cell and choose Home > Number > Percent Style. For example, a stored result near 0.2222 displays as 22.22% with two decimal places.

Can percentage difference be negative?
Not with the standard formula shown here, because ABS makes the difference nonnegative. If you need to show whether a value increased or decreased from a baseline, use percentage change and retain its positive or negative sign.

What happens when one of the values is zero?
If both inputs are zero, the average is zero and the formula cannot produce a defined percentage difference. If one is zero and the other is nonzero, the standard result is 200%. State your handling of zero values if the numbers are part of a formal report.

Does the formula work in Excel for Mac or the web?
Yes. ABS, AVERAGE, cell references, and percentage formatting are available there too. The formula syntax is the same; use the percentage-format option on the Home tab if the ribbon controls look different.

Try it: the Formula Explainer: paste any formula and see each function and reference in plain English.

More in Formulas & functions

Sources: Function behaviour and menu paths: Microsoft Support documentation for Excel. Method & sources

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