One helpful number format is the percentage (%) format. It shows values as percentages, like 20% or 55%. This is useful when calculating things like sales tax or tips. When you type a percent sign (%) after a number, Excel will automatically apply the percentage format to that cell.

Remember from math class, a percentage can also be written as a decimal. For example, 15% is the same as 0.15, 7.5% is 0.075, 20% is 0.20, and 55% is 0.55. If you want to learn more about converting percentages to decimals, check out our Math tutorials.

Percentage formatting is helpful in many situations. For example, look at the images below showing sales tax rates (5, 5%, and 0.05).

In the first spreadsheet, the calculation didn’t work right. Without the percentage format, Excel thought we wanted to multiply $22.50 by 5 instead of 5%. In the second spreadsheet, the calculation worked fine without percentage formatting. But the third one, with the percentage format, is easier to read.