Excel provides you different ways to calculate percentages. For example, you can use Excel to calculate the percentage of correct answers on a test, discount prices using various percent assumptions, or percent change between two values. Calculating a percentage in Excel is an easy two-step process. First, you format the cell to indicate the value is a percent, and then you build the percent formula in a cell.

### Format values as percentages

To show a number as a percent in Excel, you need to apply the Percentage format to the cells. Simply select the cells to format, and then click the **Percent Style (%)** button in the **Number** group on the ribbon’s **Home **tab. You can then increase (or decrease) the the decimical place as needed. (See **Rounding issues** below for more information.)

In Excel, the underlying value is always stored in decimal form. So, even if you’ve used number formatting to display something as a percentage (10%), that’s just what it is—formatting, or a symbolic representation of the underlying value. Excel always performs calculations on that underlying value, which is a decimal (0.1). To double-check the underlying value, select the cell, press Ctrl + 1, and look in the **Sample** box on the **General** category.

Here are a few things to keep in mind when formatting percentages:

**Format existing values**—When you apply percentage formatting to a cell that already has a number in it, Excel multiplies that number by 100 and adds the % sign at the end. So for example, if you type **10** into cell A2 and then apply the percentage number format, Excel will multiply your number by 100 to show it as a percentage (remember that 1% is one part of one hundred), so you’ll see **1000%** displayed in the cell, not **10%**. To get around this, you can calculate your numbers as percentages first.

For example, if you type the formula **=10/100** in cell A2, Excel will display the result as **0.1**. If you then format that decimal as a percentage, the number will be displayed as **10%**, as you ‘d expect. You can also just type the number in its decimal form directly into the cell—that is, type **0.1** and then apply percentage format.

**Rounding issues**—Sometimes what you see in a cell (e.g., 10%) doesn’t match the number you expected to see (e.g., 9.75%). To see the true percentage in the cell, rather than a rounded version, increase the decimal places. Again, Excel always uses the underlying value to perform calculations.

**Format empty cells**—Excel behaves differently when you pre-format empty cells with percentage formatting and *then* enter numbers. Numbers equal to and larger than 1 are converted to percentages by default; numbers smaller than 1 that are not preceded with a zero are multiplied by 100 to convert them to percentages. For example, if you type **10** or **.1** in a preformatted cell, you’ll see** 10%** appear in the cell. Now, if you type ** 0.1** in the cell, Excel will return 0% or 0.10% depending on the decimal setting.

**Format as you type**—If you type **10%** directly in the cell, Excel will automatically apply percentage formatting. This is useful when you want to type just a single percentage on your worksheet, such as a tax or commission rate.

**Negative percentages**—If you want negative percentages to be formatted differently—for example, to appear as red text or within parentheses—you can create a custom number format such as **0.00%;[Red]-0.00% **or** 0.00%_);(0.00%)**.

### Calculating percentages

As with any formula in Excel, you need to start by typing an equal sign (=) in the cell where you want your result, followed by the rest of the formula. The basic formula for calculating a percentage is =part/total.

In the example below, Actual Points/Possible Points = Grade %:

Say you want to reduce a particular amount by 25%, like when you’re trying to apply a discount. Here, the formula will be: =Price*1-Discount %. (Think of the “1” as a stand-in for 100%.)

To increase the amount by 25%, simply replace the minus sign in the formula above with a plus sign.

The next example is slightly more complicated. Say the earnings for your department are $2,342 in November and $2,500 in December and you want to find the percentage change in earnings between these two months. To find the answer, divide the difference between December and November earnings ($158) by the value of the November earning ($2,342).

### Learn more

See more examples of calculating percentages and learn more about how to format numbers as percentages. Also, start your free trial of Excel.

**Editor’s note 3/7/2019:
**This blog post was updated to reflect the blog’s current editorial style.