 If you can calculate percentages in Excel, it comes in handy. For example, you might need to calculate the tax on a sale, or the percentage of change in sales from last month to this month. Here’s how you do it!

## Calculate Percent Increase

To get started, let’s calculate the increase of one value over another as a percentage.

In this example, we want to find the percentage of increase in the sales of a product this month compared to last month. In the image below, you can see last month’s value of 430 in cell B3, and this month’s sales of 545 in cell C3.

To calculate the difference as a percentage, we subtract this month’s value from last month’s, and then divide the result by last month’s value.

`=(C3-B3)/B3`

The brackets around the subtraction part of the formula ensure that calculation occurs first.

To format the result as a percentage, click the “Percent Style” button in the “Number” section on the Home tab.

We see the percentage of increase is 27 percent.

If the percentage is negative, it means the sales of the product have decreased.

## Increase a Value by a Specific Percent

You can also increase a value by a specific percentage.

In this example, we want to increase the price of a product by five percent. To do this, we can multiply the product price by 1.05. This is shown in the formula below:

`=B3*1.05`

Or we could write the formula as:

`=B3*105%`

These formulas simply multiply the value by five percent more than the whole of itself (100 percent).

As a result, a 20 percent increase would be multiplied by 120 percent, and a 15 percent increase would be 115 percent (or 1.15).