Basic Percentage Formula

Percentages are really just a way to show parts of a whole. Imagine you cut a cake into 100 equal pieces. Each piece represents 1 percent of the whole cake. So if you were to eat 25 pieces, you’d have eaten 25 percent of the cake.

This simple idea helps us in many daily situations. For instance, if a store offers a 20 percent discount on a $100 shirt, that means you save $20. Or, if you’ve completed 40 percent of a book, you know exactly how far you’ve read and how much you’ve left.

The term “percent” comes from the Latin per centum, meaning “by the hundred.” To find a percentage, you divide the part by the whole and then multiply by 100.

Part / Whole * 100

For instance, if you have 50 dollars and give away 10, the formula for percentage given away as follows:

10 / 50 * 100 = 20%

How to Calculate Percentages in Excel

In Microsoft Excel, this process is even more straightforward. Excel automates some steps. This makes it quicker to calculate percentages without manually multiplying by 100.

For example, if you want to find the percentage $10 (in cell A2) is of $50 (in cell B2), you enter this percentage formula in Excel into any cell:

 = A2 / B2

After you enter this formula, Excel calculates the fraction.

how to enter percentage formula

To display your result as a percentage in Excel, you have a two easy options.

  • First, you can apply the percentage format to the cell. To do this, select the cell with your percentage formula. Then, go to the ‘Home’ tab, find the ‘Number’ group, and click the ‘Percentage Style‘ button.
  • Or, if you prefer keyboard shortcuts, you can just press Ctrl + Shift + %. You press them after selecting the cell.

Calculating Percentage Increase in Excel

In Excel, finding the percentage increase or decrease between two values is common. It shows how much a value has gone up or down over time. This can help in analyzing trends or changes in data points.

Formula for Percentage Change

The formula to determine the percentage increase or decrease is straightforward:

percentage formula

If the result is a positive number, it indicates an increase — the new value is higher than the old one.

A negative result indicates a decrease. The new value is lower than the old one.

Why -1?

Subtracting 1 in the formula for percentage of total in Excel isolates just the change, not the total.

Here’s how it works:

Dividing the new value by the old gives you a ratio that compares the new value to the old.

For instance, if the new value is double the old value, this ratio would be 2. By subtracting 1 from this ratio, you’re left with 1, which represents a 100% increase from the original.

Subtracting 1 adjusts the ratio. It focuses solely on the increase or decrease. This makes it clear by how much the value has gone up or down.

Percentage Increase or Decrease – Example

Let’s say you have a list of products along with their actual sales values and their planned budget values.

You’ll need to calculate how much the actual values differ from the budgeted amounts in percentage terms.

Calculating Percentage Increase in Excel

Steps to Calculate Percentage Increase or Decrease in Excel:

  • Understand the Formula: The formula for percentage change is:
Calculating Percentage Increase in Excel

This will show how much the actual values have gone up or down compared to the budget.

  • Enter the Formula in Excel: Click on cell D5. This is where you want the percentage change to appear. Type in this formula:
=B5/C5-1

Here, B5 represents the actual value and C5 the budget value.

Calculating Percentage Increase in Excel
  • Copy the Formula: After entering it in cell D5, drag down from the corner of the cell to fill the formula down through the rest of the table. This will apply the calculation to all corresponding rows.
  • Format as Percentage: Once the formula is filled in, select all the cells with the percentage formula and format them as percentages. To do this, go to the ‘Home’ tab, find the ‘Number’ group, and click on the ‘Percentage Style’ button. This will convert the formula results into a percentage format.

How to Increase an Amount by a Percentage

Suppose you have a list of starting prices and you want to adjust these prices by a specific percentage—either increasing or decreasing them. This is a common task when updating pricing based on new sales strategies or cost changes.

How to Add a Percentage to a Number

The formula to adjust a number by a percentage is

Starting Number * (1 + Percentage)

This formula takes the original price and increases it by a given percentage. For instance, to increase a price by 10%, you multiply the price by 1.10 (which represents 100% of the original price plus the additional 10%).

Enter the Percentage Formula in Excel

  • Position your cursor in cell C3, which is where you want the adjusted price to appear.
  • Enter the formula:
=A3 * (1 + B3)

Here, A3 holds the original price, and B3 contains the percentage by which you want to increase the price.

  • Copy the Formula: Drag the fill handle at the bottom right corner of cell C3 down to fill in the formula for other rows in your table. This will apply the same percentage increase to all listed prices.
  • Check the Result: If the starting price in cell A3 was $100 and you wanted to increase it by 10%, the formula in C3 will correctly calculate the new price as $110.

How to Enter Percentages in Excel

Entering percentages in Excel can be done in several straightforward ways, depending on how you prefer to input your data. Here’s how you can do it:

Direct Percentage Entry

Simply type the number followed by a percent sign (e.g., 30%). Excel recognizes this pattern and automatically applies the Percentage style to the cell. This converts the number into a percentage directly—typing “30%” transforms it into 30%.

Decimal Entry with Manual Formatting

If you prefer, you can enter a decimal number (e.g., 0.30 for 30%) and then manually apply the Percentage style.

To do this, after entering the number, go to the ‘Home’ tab, find the ‘Number’ group, and click on the ‘Percentage Style’ button. This will convert the decimal into a percentage.

Pre-formatting Cells

Another effective method is to first apply the Percentage style to the cell before entering your number. Select the cell, apply the Percentage style as described above, and then enter your number as a whole number (e.g., entering 30 will be automatically formatted as 30%).

❗ Be cautious with how you enter values. If you enter a whole number like 30 and then apply the Percentage style afterward without indicating it as a percentage or decimal, Excel will interpret this as 3000%. This happens because Excel multiplies the number by 100 to convert it to a percentage. Thus, entering “30” and converting it later will not yield “30%” but “3000%”.

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Enhance your learning experience by downloading our workbook. Practice the techniques discussed in real-time and master how to calculate percentage in Excel with hands-on examples. Download the workbook here and start applying what you’ve learned directly in Excel.

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Leila Gharani

I'm a 6x Microsoft MVP with over 15 years of experience implementing and professionals on Management Information Systems of different sizes and nature.

My background is Masters in Economics, Economist, Consultant, Oracle HFM Accounting Systems Expert, SAP BW Project Manager. My passion is teaching, experimenting and sharing. I am also addicted to learning and enjoy taking online courses on a variety of topics.