How to Calculate Percentages in Excel: Formulas and Examples

Key Takeaways

• Use the formula =Part/Total to find what percentage one number is of another, then format the cell as a percentage.

• Calculate percentage increase with =Value*1.XX or percentage decrease with =Value*(1-0.XX), where XX is the percentage.

• The percent change formula =(New Value-Old Value)/Old Value shows whether values are trending up or down.

• Press Ctrl + Shift + % to quickly format any cell as a percentage in Excel.

Understanding Percentage Calculations in Excel

Whether you need to figure out how much expenses went up last quarter or calculate a discount on a purchase order, knowing how to calculate percentages in Excel is an essential workplace skill. The percentage formula in Excel follows straightforward patterns once you understand the logic behind each type of calculation.

This guide walks through the most common percentage scenarios with formulas and examples, using a simple travel expense spreadsheet. Here are the types of percentage calculations covered:

• Percentage increase (finding a new total after a percentage goes up)

• Percentage decrease (finding a new total after a percentage goes down)

• Percent amount (isolating just the percentage portion)

• Percent change (comparing two values to see the trend)

• Percentage of a total (determining what share one value is of another)

Use the quick-reference table below to find the right Excel percentage formula examples for your situation:

For these examples, we have a simple sheet of travel expenses and you are after the percentage results of prices going up or down for the total and for the individual months.

How to Format Cells as Percentages in Excel

Before diving into formulas, it helps to know how to format cells as percentages so your results display correctly. Excel stores percentages as decimals internally, meaning 75% is actually stored as 0.75. Formatting controls how that value appears on screen.

There are two ways to apply percentage formatting:

1. Select the cells you want to format, go to the Home tab and click the Percent Style button in the Number group. This converts the displayed value to a percentage with no decimal places.

2. Use the keyboard shortcut Ctrl + Shift + %. This applies the same Percent Style formatting instantly.

A common mistake is typing a whole number like 75 into a cell that is already formatted as a percentage. Because Excel treats the entry as 75.00 and then displays it as a percentage, the result shows as 7500% instead of 75%. To avoid this, either enter the value as a decimal (0.75) before formatting or apply the percentage format after you have entered your numbers.

Percent Increase

To calculate the result after a percentage increase, multiply the original value by 1 plus the percentage as a decimal. Let's say you anticipate more travel the following year and want to know what the cost will be if the expenses increase by 8%.

Tip: Excel lets you type percentages either with a percent sign or as a decimal. For example, you can enter 20% as either 20% or 0.2 (with or without the leading zero). Excel will treat them both the same.

In B19, enter:

=B18*1.08

Or if you like, enter it as:

=B18*108%

The amount will be 77,555.

Percent Decrease

If you think travel expenses will decrease by 8% instead, enter this in B20:

=B18*92%

Or if you like, enter it as:

=B18*.92

The result will be 66,065.

Maybe it's late in the day and you don't want to calculate in your head that 92% is an 8% decrease. You can enter the formula this way for the same result:

=B18-B18*0.08

You can also write this as =B18*(1-0.08), which mirrors the structure of the increase formula and makes the logic easier to follow.

Tip: Remember the Order of Operations is Parenthesis, Exponents, Multiplication, Division, Addition, Subtraction. (Please Excuse My Dear Aunt Sally.)

Percent Amount

But what if you want to see the 8% amount itself, not the new total? The formula in B21 would be:

=B18*0.08

OR

=B18*8%

This is the formula you'd use to calculate sales tax in New York City, if B18 contained the total sale. This same approach works for calculating tips, discounts, commissions or any scenario where you need to isolate the percentage amount. These percentage principles also underpin more advanced Excel finance formulas used for loan payments, investment returns and depreciation.

While all this math is correct, you might prefer to put the percentage in its own cell, rather than hard-coding it into the formulas. That way, you can change the percentage without having to rewrite the formulas.

Percent Change

Finally, we might want to calculate the percentage change between two numbers. That would give us a clear picture of whether costs were heading up (a positive percentage) or heading down (a negative percentage). In this expense sheet, we'll calculate the percent change from one month to the next and put the formulas down column C. Once you have these values, you can also create a chart with date data to visualize the trends.

The general rule to calculate a percentage change is:

=(new value-old value)/old value

Since January is the first month, it doesn't have a percentage change. The first change will be in February, so this is the formula for C6:

=(B6-B5)/B5

By default, Excel displays this as a decimal, so click the Percent Style button on the Home tab to format it as a percent.

Tip: The keyboard shortcut for Percent Style is Ctrl + Shift + %

Now auto-fill the formula down to the bottom: roll the mouse pointer over the dot in the lower-right corner of the cell that shows -16% and double-click the mouse. That's a faster way of filling down to the bottom of the column than dragging down. To make positive and negative changes stand out at a glance, apply conditional formatting to color-code the results.

How to Find the Percentage of a Total

One of the most common reasons to calculate percentages in Excel is to find what percentage one number is of another. The formula is straightforward:

=Part/Total

For example, if cell B2 contains an individual monthly expense of 5,000 and cell B10 contains the sum of total expenses of 50,000, entering =B2/B10 returns 0.10. Format the cell as a percentage and it displays as 10%.

To calculate the percentage of a total for multiple rows, use an absolute reference for the total cell. For example, enter =B2/$B$10 in the first row. The dollar signs lock the reference to B10 so that when you copy the formula down the column, the denominator stays fixed while the numerator adjusts to each row. Without the absolute reference, the total cell reference would shift as you copy the formula and produce incorrect results.

How to Find the Total from a Percentage and Amount

Sometimes you know the amount and the percentage it represents but need to find the original total. In this case, divide the amount by the percentage:

=Amount/Percentage

For example, if you know that 125 represents 25% of a total, entering =125/25% (or =125/0.25) returns 500. This is useful when working backward from a known discount amount, tax figure or commission payment to determine the base value.

Tips for Working with Percentages in Excel

Keep these practical tips in mind when working with percentage formulas:

• Use absolute references ($) when copying percentage formulas down a column with a fixed denominator, such as =B2/$B$10, so the total cell does not shift
• Place percentage values in their own cells rather than hard-coding them into formulas. This makes it easy to update the percentage in one place without rewriting every formula that uses it
• Remember that Excel stores percentages as decimals internally. A cell displaying 75% actually contains 0.75
• Use Ctrl + Shift + % as a quick formatting shortcut instead of navigating through the ribbon each time
• Double-check whether your source data is already in decimal form before applying percentage formatting. Applying percentage format to a cell that already contains 0.75 displays 75%, but applying it to a cell containing 75 displays 7500%

Conclusion

These percentage formulas cover the most common calculations you will encounter in the workplace, from tracking expense changes to figuring out what share each line item represents of a total. Once you learn the patterns, you can adapt them to virtually any Excel scenario.

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