Percentage in Excel: Formula & Examples

To calculate a percentage in Excel, you divide the part by the total and then format the result as a percentage — the core formula is =part/total. For example, if cell A1 contains 25 and B1 contains 100, entering =A1/B1 and applying the Percent format gives 25%. Excel stores percentages as decimal fractions (0.25 equals 25%), so the formatting step is what turns the decimal into the percentage you see.

Formula

The general formula for percentage in Excel is:

Percentage = (Part ÷ Total) × 100

In Excel terms, you write =part/total and then format the cell as a percentage. Excel multiplies the decimal by 100 and adds the % symbol automatically when you apply the Percent format (Home → Number → %). If you prefer to keep the result as a plain number, you can write =part/total*100 — but then the cell shows a number like 25, not 25%.

Variables:

• Part — the numerator, the specific value you are comparing (e.g., sales for one product).
• Total — the denominator, the whole or baseline (e.g., total sales).
• Percentage — the result, expressed as a number between 0 and 100 (or as a decimal when formatted as %).

Worked Example

Using the default values from the calculator: Part = 25, Total = 100.

1. Enter 25 in cell A1 and 100 in cell B1.
2. In cell C1, type =A1/B1 and press Enter. The result is 0.25.
3. Select cell C1, go to the Home tab, and click the % button (or press Ctrl+Shift+%). The cell now shows 25%.

The calculator above computes (25/100)*100 = 25.00%, which matches the Excel result when you format the decimal as a percentage.

How to Calculate Percentage Increase or Decrease

A common task is finding the percent change between two values. The formula is:

Percent Change = ((New Value – Old Value) / Old Value) × 100

In Excel: =(B2-A2)/A2 where A2 is the old value and B2 is the new value. Format the cell as % to see the change. For example, if sales went from 50 to 75, the formula gives (75-50)/50 = 0.5, which formats as 50% — a 50% increase. If the result is negative, it represents a decrease (e.g., -20% means a 20% drop).

How to Calculate a Percentage of a Total in Excel

Often you have a list of values and want each one as a percentage of the grand total. Suppose you have sales in cells A1:A5 and the total in B1.

1. In cell C1, enter =A1/$B$1 (the dollar signs lock the reference to the total when you copy the formula down).
2. Press Enter, then drag the fill handle down to C5.
3. Format C1:C5 as percentages.

The absolute reference $B$1 ensures that every row divides by the same total. Without the dollar signs, copying the formula would shift the total reference and give wrong results.

Common Mistakes and How to Avoid Them

• Forgetting to format as % — If you don’t apply the percent format, Excel shows 0.25 instead of 25%. Use the % button or the shortcut Ctrl+Shift+%.
• Multiplying by 100 when you don’t need to — When you format as %, Excel already multiplies by 100. Writing =part/total*100 and then formatting as % will show 2500%, which is wrong.
• Using the wrong denominator — For percentage increase, the denominator is always the old value, not the new one. Using the new value gives a different, incorrect result.
• Dividing by zero — If the total is 0, Excel returns a #DIV/0! error. Check your data or use an IFERROR function to handle blanks.

Using Percentages in Other Excel Formulas

Percentages are just decimals in Excel, so you can use them directly in formulas. For example, to add 20% tax to a price in cell A1, use =A1*1.2 (or =A1*120%). To find what 15% of 200 is, use =200*15% — Excel treats 15% as 0.15 and returns 30. You can also use the percentage in cell references, like =A1*B1 where B1 contains 15% formatted as a percentage.

Limitations and When to Use a Different Approach

The basic part/total formula works for most percentage calculations, but it has limitations. It assumes the total is a single, static number. For dynamic ranges, you might use the SUM function: =A1/SUM($A$1:$A$5). If you need to calculate percentage change over time with negative numbers, the standard formula can produce misleading results (e.g., going from -10 to 20 gives a 300% change, which may not be meaningful). In those cases, consider using a different metric like absolute change or a percentage of absolute values. Also, remember that Excel’s percent format only affects display, not the underlying value — so rounding may appear different from the actual calculation.

Frequently Asked Questions

How do I calculate a percentage in Excel without formatting?

Use the formula =part/total*100 and leave the cell as General or Number. This gives a plain number like 25, which you can then use in other calculations. However, if you later apply the % format, it will show 2500%, so be consistent.

Why does Excel show 0.25 instead of 25%?

Because the cell is not formatted as a percentage. Excel stores percentages as decimals (0.25 = 25%). To display the % symbol, select the cell and click the Percent Style button in the Number group on the Home tab, or press Ctrl+Shift+%.

How do I calculate a percentage of a total when the total is in a different cell?

Use an absolute reference to lock the total cell. For example, if the total is in B1 and the part is in A1, enter =A1/$B$1 and copy down. The $ signs prevent the total reference from changing as you copy.

How do I calculate percentage increase in Excel?

Use =(new-old)/old and format as %. For instance, if old is in A1 and new is in B1, enter =(B1-A1)/A1. A positive result is an increase, a negative result is a decrease.

Can I use a percentage in a formula like a regular number?

Yes. A cell formatted as 20% is stored as 0.2, so you can multiply, add, or divide with it directly. For example, =A1*20% gives 20% of A1.

What does #DIV/0! mean in a percentage formula?

It means you are dividing by zero. Check the denominator cell — it may be empty or contain a zero. Use the IFERROR function, like =IFERROR(A1/B1,0), to display 0 instead of the error.

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in part | Part value | - | 25 | 0
in total | Total value | - | 100 | 0
out pct | Percentage | % | (part / total) * 100 | 2