# How to Calculate Percentage Increases or Decreases in Excel

Microsoft Excel is great for basic and complicated calculations alike, including percentage differences. If you’re struggling to calculate percentage increases or decreases on paper, Excel can do it for you.

If you remember your school math, the process for calculating percentages in Excel is pretty similar. Here’s how to use Excel to calculate percentage increases and decreases. And perform other percentage calculations like percentages of a number.

## Calculating Percentage Increases in Excel

Percentage increases involve two numbers. The basic mathematical approach for calculating a percentage increase is to subtract the second number from the first number. Using the sum of this figure, divide this remaining figure by the original number.

To give you an example, the cost of a household bill costs **$100** in September, but **$125** in October. To calculate this difference, you could use the formula **=SUM(NEW-OLD)/OLD** or for this example, **=SUM(125-100)/100 **in Excel.

If your figures are in separate cells, you can replace numbers for cell references in your formula. For example, if September’s bill amount is in cell **B4** and October’s bill amount is in cell **B5,** your alternative Excel formula would be **=SUM(B5-B4)/B4**.

The percentage increase between September and October is **25%**, with this figure shown as a decimal number (**0.25**) by default in Excel using the formula above.

If you want to display this figure as a percentage in Excel, you’ll need to replace the formatting for your cell. Select your cell, then click the **Percentage Style** button in the **Home **tab, under the **Number** category.

You can also right-click your cell, click **Format Cells**, then select **Percentages** from the **Category > Number** menu to achieve the same effect.

## Calculating Percentage Decreases in Excel

To calculate the percentage decrease between two numbers, you’ll use an identical calculation to the percentage increase. You subtract the second number from the first, then divide it by the first number. The only difference is that the first number will be smaller than the second number.

Continuing the above example, if a household bill is **$125** in October, but it returns to **$100** in November, you would use the formula **=SUM(NEW-OLD)/OLD** or in this example, **=SUM(100-125)/125**.

Using cell references, if October’s bill amount of **$125** is in cell **B4** and November’s bill amount of **$100** is in cell **B5**, your Excel formula for a percentage decrease would be **=SUM(B5-B4)/B4**.

The difference between October and November’s figures is **20%**. Excel displays this as a negative decimal number (**-0.2**) in cells **B7** and **B8** above.

Setting the cell number type to **Percentages** using the **Home > Percentage Styles button** will change the decimal figure (**-0.2**) to a percentage (**-20%**).

## Calculating a Percentage as a Proportion

Excel can also help you calculate a percentage as a proportion. This is the difference between one number, as your complete figure, and a smaller number. This requires an even simpler mathematical calculation than a percentage change.

To give you an example, if you have a debt of **$100,** and you’ve already paid **$50**, then the proportion of the debt you’ve paid (and coincidentally still owe) is **50%**. To calculate this, you simply **divide 50 by 100**.

In Excel, the formula to calculate this example would be **=50/100**. Using cell references, where **$100** is in cell **B3** and **$50** is in cell **B4**, the formula required is **=B4/B3.**

This uses only a basic division operator to give you the result as a decimal number (**0.5**).

Converting this cell number type to **Percentages** by clicking **Home > Percentage Style button** will show the correct percentage figure of **50%**.

## How to Calculate Percentages of a Number

Calculating the percentage of a number is something that you’ll encounter in day-to-day life. A good example would be an item for sale, where a discount of **20%** is being applied to the original price of **$200**. A store employee would need to know what 20% of $200 was. They could then subtract this number from the original price to provide the discounted price.

This requires another simple mathematical calculation in Excel. Only the multiplication operator (*****) and percentage sign (**%**) are used here. To calculate what **20% **of the original **$200** price is, you can use either **=20%*20****0** or **=0.2*200** to make the calculation in Excel.

To use cell references, where **20%** is in cell **B4 **and the original price of **$200** is in cell **B5**, you could use the formula **=B4*B5** instead.

The result is the same, whether you use **20%**, **0.2**, or separate cell references in your formula. **20% of $200** equals **$40**, as shown in cells **B6 to B8 **above.

## Using Excel for Complex Calculations

As this guide shows, Excel is great for simple calculations, but it handles more complex ones, too. Calculations using functions like the VLOOKUP function are made easy, thanks to the built-in function search tool.

If you’re new to Excel, take advantage of some Excel tips every user should know to improve your productivity further.