The basic formula for percent increase

To calculate percent increase in Excel, use this formula: =(New Value - Old Value) / Old Value. This gives you the increase as a decimal. Multiply by 100 to show it as a percentage, or format the cell as a percentage and Excel handles the multiplication for you.

The formula works because you are finding how much the value changed, then dividing that change by what you started with. If a price went from $50 to $60, the change is $10, and $10 divided by $50 is 0.20, or 20 percent.

Key Takeaways

  • The percent increase formula is (New Value - Old Value) / Old Value, entered as =(B2-A2)/A2 when your old value is in column A and new value is in column B.
  • Format the result cell as Percentage to show the answer as a percent without manually multiplying by 100.
  • If your old value is zero, Excel shows a #DIV/0! error because you cannot divide by zero — this is expected behavior, not a mistake.
  • Copy the formula down to calculate percent increase for multiple rows at once by selecting the cell and dragging the fill handle to the rows below.

Setting up your data in Excel

Start by putting your old values in one column and your new values in another. For example, put the starting price in column A and the ending price in column B. Make sure each pair of values is on the same row — old value in A2, new value in B2, and so on down the sheet.

Leave a column empty for your results, or use column C. Click on the first empty cell where you want the percent increase to appear. This is usually C2 if your data starts in row 2.

Entering the formula step by step

Type the formula exactly as shown: =(B2-A2)/A2. Start with the equals sign so Excel knows you are entering a formula, not text. Replace B2 and A2 with the actual cell references where your new and old values are located.

Press Enter. Excel calculates the result and shows it as a decimal — for example, 0.2 for a 20 percent increase. This decimal is correct, but it does not look like a percentage yet. Do not delete it or re-enter the formula.

Formatting the result as a percentage

Click on the cell with your result. Look at the toolbar at the top of Excel and find the button that looks like a percent sign (%). Click it. The decimal instantly converts to a percentage — 0.2 becomes 20%, 0.05 becomes 5%, and so on.

If you do not see a percent button in your toolbar, right-click the cell, select Format Cells, choose Percentage from the Category list on the left, and click OK. Both methods do the same thing.

Copying the formula to multiple rows

If you have many rows of data, you do not need to type the formula in each cell. Click on the cell with your formula (the one you just created). Look at the bottom right corner of the cell — you will see a small square. Click and drag that square down to the last row of your data. Excel copies the formula to every row and adjusts the cell references automatically.

For example, if you drag from C2 down to C10, the formula in C3 becomes =(B3-A3)/A3, the formula in C4 becomes =(B4-A4)/A4, and so on. You do not have to type anything else — just drag and release.

Handling common problems

If you see #DIV/0! in a cell, it means your old value is zero. You cannot divide by zero, so Excel shows an error. This is normal and expected. If you need to handle this situation, you can use an IF statement to check whether the old value is zero before calculating: =IF(A2=0,"N/A",(B2-A2)/A2). This shows "N/A" instead of an error when the old value is zero.

If your result shows as a decimal and the percent button did not work, make sure the cell is actually selected before clicking the percent button. Sometimes the button is greyed out if you have multiple cells selected or if the cell contains text instead of a number.

If your percent looks wrong — for example, showing 2000% instead of 20% — you may have already multiplied by 100 in your formula. Delete the *100 part if you added it, or just format the cell as a decimal instead of a percentage.

Calculating percent increase with a single formula

If you want the answer to show as a percentage in one step without formatting, type: =(B2-A2)/A2*100. This multiplies the result by 100 and shows it as a number — 20 instead of 0.2. The downside is that it does not look like a percentage (no % sign), so most people prefer to use the simpler formula and format the cell instead.

Either method is correct. Choose whichever one makes sense for how you want to present your data. If you are building a report that other people will read, formatting as a percentage looks more professional and is easier to understand at a glance.

Frequently Asked Questions

What if my old value is negative?

The formula still works mathematically, but the result can be confusing. If you go from -10 to 10, the formula shows a 200% increase, which is technically correct but may not match how you think about the change. For negative numbers, consider whether percent increase is the right metric or if you need a different calculation.

Can I calculate percent decrease the same way?

Yes. The formula =(New Value - Old Value) / Old Value works for both increase and decrease. If the new value is smaller, the result is negative — for example, -0.2 for a 20% decrease. Format it as a percentage and it shows -20%.

How do I show only one decimal place in my percentage?

Right-click the cell with your percentage, select Format Cells, choose Percentage, and change the Decimal Places field to 1. Click OK. Now 20.5% shows as 20.5% instead of 20.50%.

What if I want to calculate the new value when I know the old value and the percent increase?

Use the formula =A2*(1+B2) where A2 is the old value and B2 is the percent increase as a decimal. If the percent is already formatted as a percentage in the cell, Excel treats it as a decimal automatically. For example, if the old value is 100 and the increase is 20%, the result is 120.