Calculate Percentage in Excel

Percentages are used in almost every spreadsheet: exam marks, sales share, price increase, discount, GST, attendance, and growth. Excel does not have one special percentage function. You calculate a percentage with a simple division or multiplication, and then format the result as a percentage.

This article shows how to calculate percentages in Excel for the five most common situations, with the formula, output, and explanation for each.

How Excel Stores Percentages

Excel stores a percentage as a decimal number. The value 0.25 is the same as 25%. When you apply the Percentage format to a cell, Excel only changes how the number is displayed.

To apply the format, select the cells and click the % button in the Number group on the Home tab, or press Ctrl + Shift + %.

Because of this, you should not multiply by 100 in your formula when the cell is formatted as a percentage. Excel adds the percent sign and the multiplication for you.

1. Percentage of a Total

Use this to find what part one number is of another number. The formula is:

=Part / Total

Example: Exam percentage

In D2, enter:

=B2/C2

Then format D2 as a percentage.

Output:

90%

Explanation:

Excel divides 450 by 500 and gets 0.9. The Percentage format displays this as 90%.

Percentage Share of Each Item

To find the share of each row in the grand total, divide each value by the total and lock the total cell with absolute references.

In C2, enter this formula and copy it down to C4:

=B2/SUM($B$2:$B$4)

Explanation:

The total of B2:B4 is 100000. The dollar signs keep the range fixed when the formula is copied, so every row is divided by the same total. Without the $ signs, the range would move down and give wrong results. This is explained in the absolute and relative reference questions in Excel Interview Questions.

2. Percentage Change (Increase or Decrease)

Use this to compare an old value and a new value. The formula is:

=(New Value - Old Value) / Old Value

Example: Sales growth

If September is in B2 and October is in B3, enter this in C3:

=(B3-B2)/B2

Output:

15%

Explanation:

The sales increased by 92000 − 80000 = 12000. Dividing 12000 by the old value 80000 gives 0.15, which is 15%. If the new value is smaller, the result is negative. For example, a fall from 92000 to 80000 gives (80000 − 92000) / 92000 = −0.1304, which Excel shows as −13.04% when two decimal places are used. A negative percentage means a decrease.

3. Increase or Decrease a Number by a Percentage

Use this to find a new price after an increase or a discount.

Increase by a percentage:

=Price * (1 + Percentage)

Decrease by a percentage:

=Price * (1 - Percentage)

Example:

=B2*(1+C2) =B3*(1-C3)

Output:

2200 1700

Explanation:

A 10% increase means the new price is 110% of the old price, so Excel multiplies 2000 by 1.10 and gets 2200. A 15% discount means the new price is 85% of the old price, so 2000 × 0.85 = 1700.

4. Find the Percentage of a Number

Use this to find a percentage amount such as GST, commission, or tax.

Example: 18% GST on 5000

=5000*18%

Output:

900

To get the final bill amount, add the GST to the price:

=5000+5000*18%

Output:

5900

Explanation:

Excel reads 18% as 0.18, so 5000 × 0.18 = 900. In a real sheet, keep the price in one cell and the GST rate in another cell, for example =B2*C2, so you can change the rate without editing the formula.

5. Find the Original Value from a Percentage

Sometimes you know the final amount and the percentage, and you need the original value. For example, a value of 450 is 90% of the total. The formula is:

=Part / Percentage =450/90%

Output:

500

Explanation:

Since 450 is 90% of the total, dividing 450 by 0.9 gives the total, which is 500.

Common Percentage Mistakes in Excel

• Showing 9000% instead of 90%: This happens when the value is 90 and the cell is formatted as a percentage. Excel multiplies it by 100 for display. Use 0.9 or 90% as the value.
• #DIV/0! error: This appears when the old value or total is zero. Use =IFERROR((B3-B2)/B2,0) to show 0 instead of the error.
• Wrong decimal places: Use the Increase Decimal and Decrease Decimal buttons on the Home tab to control how many digits are shown. The stored value does not change.

Important Points About Percentages in Excel

• Excel stores a percentage as a decimal, so 25% is stored as 0.25.
• Do not multiply by 100 when the cell uses the Percentage format.
• Percentage of total is Part / Total, and percentage change is (New − Old) / Old.
• Use Price * (1 + %) for increases and Price * (1 - %) for discounts.
• Use absolute references such as $B$2:$B$4 when every row must use the same total.