How to Calculate Percentages in Excel and Google Sheets
Published on January 14, 2026 • By iPercentageCalculator Team
Spreadsheets are the backbone of modern business. Whether you are managing a household budget in Google Sheets or analyzing complex sales data in Microsoft Excel, knowing how to handle percentages is a non-negotiable skill.
The good news? Excel makes percentages incredibly easy because it automatically handles the "multiply by 100" part of the math for you. Let’s look at the three most common ways to use them.
1. Calculating the Percentage of a Total
If you have a list of expenses and you want to know what percentage of your total budget each item represents, use a simple division formula.
Step-by-Step:
- Enter your amount in cell A2 and your total in cell B2.
- In cell C2, type
=A2/B2. - Press Enter. You will see a decimal (like 0.25).
- Click the % (Percent Style) button on the Home tab to turn 0.25 into 25%.
2. Calculating Percentage Change (Increase or Decrease)
To see how much your sales grew from last month to this month, you need the "New minus Old" formula.
Example: If last month's sales are in cell A2 and this month's are in B2, your formula is =(B2-A2)/A2. This is essential for tracking growth trends.
3. Applying a Percentage Increase to a Price
If you want to increase a price by a certain percentage (like adding a 15% tax or markup), use this formula:
$B$1) if you are pulling a tax rate from a single cell so you can drag the formula down your entire list!
4. Troubleshooting Common Excel Percentage Errors
Even for professionals, Excel can sometimes return unexpected results when working with percentages. Here are the most common issues and how to fix them:
The Fix: Use the
IFERROR function. For example: =IFERROR((B2-A2)/A2, 0). This tells Excel to display a 0 instead of an error message.
Understanding the "Multiply by 100" Confusion
A frequent mistake is manually multiplying by 100 in your formula (e.g., =(A2/B2)*100) and then clicking the Percent Style button. This will result in a number that is 100 times too large (e.g., 2500% instead of 25%).
Expert Tip: Always remember that in Excel, 1 is equal to 100%. Therefore, 0.25 is exactly 25%. Let Excel's formatting tools do the heavy lifting for you rather than adding extra steps to your math formulas.
Why do my percentages not add up to 100%?
If you have a column of percentages that totals 99.9% or 100.1%, it is usually due to rounding for display. Excel may be rounding 25.44% to 25.4% for your view, but it still uses the exact hidden decimals for its internal math. To fix this, increase the decimal places shown using the "Increase Decimal" button on the Home tab.
Conclusion
Mastering these Excel and Google Sheets formulas will save you hours of manual work and ensure your data reports are professional and accurate. However, we know that sometimes you just need a quick answer without setting up a spreadsheet.
For those moments, our [online percentage calculator](../index.html) is optimized for mobile and desktop, helping you get the job done in seconds without any complex formulas.