The basic addition formula in Excel

To add numbers in Excel, you type an equals sign, then the cell addresses or numbers you want to add, separated by plus signs. For example, if you want to add the number in cell A1 to the number in cell B1, you type =A1+B1 and press Enter. Excel shows you the result in that cell.

You can add as many numbers as you need in a single formula. If you want to add A1, B1, and C1 together, type =A1+B1+C1. You can also add actual numbers directly: =5+10+3 will give you 18. Most people mix both — adding some cells and some fixed numbers in the same formula.

The equals sign at the start tells Excel that what follows is a formula, not just text. Without it, Excel treats your entry as a label and does nothing with it.

Key Takeaways

  • Every formula starts with an equals sign, followed by cell addresses or numbers separated by plus signs.
  • The SUM function is faster than typing plus signs when you need to add many cells in a row or column.
  • You can copy a formula down or across to explore it to multiple rows or columns at once.
  • Excel recalculates your formula automatically whenever any of the numbers in the cells you referenced change.

Using the SUM function for longer lists

When you have many numbers to add — say, ten cells in a column — typing =A1+A2+A3+A4+A5+A6+A7+A8+A9+A10 is tedious and error-prone. Instead, use the SUM function. Type =SUM(A1:A10) and Excel adds all the cells from A1 through A10 in one step.

The colon between A1 and A10 means "all cells in this range." You can use SUM with any range: =SUM(B5:B20) adds cells B5 through B20. You can also add multiple separate ranges if they are not next to each other: =SUM(A1:A5,C1:C5) adds the first five cells in column A and the first five cells in column C.

SUM is also useful because it ignores empty cells. If you have a list with gaps, SUM still works correctly. It only adds the cells that contain numbers.

Copying formulas to other cells

Once you write a formula in one cell, you can copy it to other cells and Excel adjusts the cell addresses automatically. If you type =A1+B1 in cell C1, then copy that formula down to C2, Excel changes it to =A2+B2. This is called a relative reference — the formula moves with you.

To copy a formula, click the cell that contains it, then click and drag the small square in the bottom right corner of the cell downward or to the right. Excel fills in the formula for each new cell, adjusting the addresses as it goes. You can also copy the cell (Ctrl+C on Windows, Command+C on Mac), select the range where you want it, and paste (Ctrl+V or Command+V).

If you want the formula to always refer to the same cell no matter where you copy it, use a dollar sign. Type =$A$1+B1 and when you copy it down, the A1 stays the same but B1 becomes B2, B3, and so on. This is useful when you have a fixed number (like a tax rate in one cell) that you want to use in many calculations.

Checking your work and fixing errors

If a formula gives you a result that looks wrong, click the cell and look at the formula bar at the top of the screen — it shows exactly what formula is in that cell. Check that you are adding the right cells and that you did not accidentally include a cell you meant to skip.

If you see an error message like #VALUE! or #REF!, it usually means one of your cells contains text instead of a number, or you referenced a cell that no longer exists. Click the cell with the error and fix the formula. You can also use the Trace Error feature (in the Formulas tab on Windows) to see which cells the formula is pulling from.

A common mistake is forgetting the equals sign at the start. If you type A1+B1 without the equals sign, Excel treats it as text and shows it exactly as you typed it, not the sum. Just click the cell, add the equals sign at the beginning, and press Enter again.

Adding cells with conditions

Sometimes you want to add only cells that meet a certain condition. For example, you might have a list of sales numbers and want to add only the ones above $100. Use the SUMIF function for this: =SUMIF(A1:A10,">100") adds only the cells in A1 through A10 that contain a number greater than 100.

You can use any comparison: =SUMIF(A1:A10,"<50") adds cells less than 50, and =SUMIF(A1:A10,"=25") adds only cells that equal exactly 25. If you want to add cells based on a condition in a different column — for example, add sales only from a specific region — use SUMIFS: =SUMIFS(B1:B10,A1:A10,"North") adds numbers in column B only where column A says "North".

Adding across sheets and workbooks

You can add cells from different sheets in the same workbook. If you have a sheet called "January" and another called "February," and you want to add cell A1 from both, type =January!A1+February!A1. The exclamation mark tells Excel to look in a different sheet. On a Mac, use a period instead: =January.A1+February.A1.

Adding cells from a different workbook (a separate Excel file) works the same way, but you need the full file path. This gets complicated quickly, so most people avoid it unless they have a good reason. If you find yourself doing this often, it usually means your data is organized in a way that makes the work harder than it needs to be.

Frequently Asked Questions

What is the difference between typing =A1+B1 and =SUM(A1:B1)?

Both give the same result when you are adding just two cells. SUM is faster and clearer when you have many cells to add. SUM also handles empty cells better — it ignores them, while a formula with plus signs treats them as zero. For most people, SUM is the better habit to build.

Can I add cells that are not next to each other?

Yes. Use =SUM(A1,A5,A10) to add only those three cells, or =SUM(A1:A5,C1:C5) to add two separate ranges. Separate each range or cell with a comma.

Why does my formula show the formula itself instead of the answer?

You probably forgot the equals sign at the start. Click the cell, add = before the formula, and press Enter. If the cell is formatted as text, right-click it, choose Format Cells, and change the format to Number.

What happens if I change a number in one of the cells I am adding?

Excel recalculates the formula automatically and updates the result. You do not have to do anything — the sum changes when ready whenever any of the cells it references change.

Can I add cells from a Google Sheet into Excel?

Not directly with a formula. You would need to copy the numbers from Google Sheets and paste them into Excel first. If you need to work with data in both places regularly, consider keeping it all in one tool instead.