Math & aggregation
How to Calculate Percentage in Excel (Formulas and Tips)
Percentages in Excel come down to a few simple formulas plus the Percent number format. The format does the heavy lifting: it multiplies the cell by 100 and adds the % sign, so a result of 0.25 displays as 25%.
This guide covers the four calculations you will use most: what percent one number is of another, percent change between two numbers, and adding or subtracting a percentage from a value, all with the right formatting.
Percentages syntax
=part / total | Argument | Required | What it does |
|---|---|---|
part | Required | The portion you are measuring, e.g. one region's sales. |
total | Required | The whole that the part belongs to, e.g. total sales. |
percent change | Optional | For change over time use =(new - old) / old, which gives the increase or decrease as a decimal. |
Note: Format the result cell as Percent (Ctrl+Shift+5) so 0.25 shows as 25%; do not multiply by 100 yourself or you will get 2500%. Works the same in Google Sheets.
Examples
Real, copy-paste-ready formulas.
1. What percent of the total
=B2 / $B$10 Divides the part by the total. Format the cell as Percent and the decimal becomes a percentage. Locking $B$10 lets you copy the formula down for every row.
2. Percent change between two numbers
=(B2 - A2) / A2 Subtract the old value from the new, then divide by the old value. A positive result is an increase, negative is a decrease. Format as Percent to read it as, say, 12%.
3. Increase a value by a percentage
=A2 * (1 + 0.15) Multiplying by 1.15 adds 15% in one step. Put the rate in a cell and use =A2 * (1 + $C$1) so you can change the percentage in one place.
4. Find a percentage of a number
=A2 * 20% You can type 20% directly; Excel reads it as 0.2. This returns one fifth of the value, handy for tax, tips, or commission.
How to write Percentages step by step
- 1
Click the result cell and type = to start the formula.
- 2
For a share of the total, type the part cell, a slash /, then the total cell (lock the total with F4).
- 3
For percent change, type =( the new cell minus the old cell ) / the old cell.
- 4
Press Enter to see the decimal result (e.g. 0.25).
- 5
Select the cell and press Ctrl+Shift+5 (or click the % button) to format it as a percentage.
- 6
Copy the formula down the column to apply it to every row.
Common errors and fixes
| Error | Why it happens | How to fix it |
|---|---|---|
#DIV/0! | The total or old value is zero or blank, so Excel cannot divide by it. | Wrap the formula in IFERROR, e.g. =IFERROR((B2-A2)/A2, 0), or make sure the denominator is not empty. |
Result shows 2500% instead of 25% | You multiplied by 100 and also applied the Percent format, doubling up. | Use the plain ratio (=B2/B10) and let the Percent format add the times-100, or drop the format if you multiplied yourself. |
Shows a decimal like 0.25, not 25% | The cell is in General or Number format. | Apply the Percent format with Ctrl+Shift+5 so the decimal displays as a percentage. |
Percent change sign looks wrong | Old and new values were swapped in the formula. | Use =(new - old) / old; the new value goes first inside the brackets, divided by the old value. |
Frequently asked questions
How do I calculate percent change in Excel?
Use =(new - old) / old and format the result as a percentage. For example, =(B2 - A2) / A2 shows the growth from A2 to B2; a positive number is an increase and a negative number is a decrease.
Why does my percentage show as a huge number?
You likely multiplied by 100 and also applied the Percent format. The format already multiplies by 100, so use the plain ratio (=B2/B10) and let the format add the % sign.
How do I add a percentage to a price?
Multiply by 1 plus the rate: =A2 * (1 + 0.15) adds 15%. To subtract, use =A2 * (1 - 0.15). Storing the rate in a cell keeps it easy to change.
How do I find what percent one number is of another?
Divide the part by the total and format as Percent: =B2 / $B$10. Lock the total with $ so you can fill the formula down the column.