Need to add numbers together? SUM is Excel’s most fundamental function. It totals any range of cells, ignores text automatically, and saves you from manual addition errors. Every Excel user starts here.
To download the exercise file for this function, click here.
What Makes SUM Useful
SUM is the workhorse of spreadsheet calculations:
- Lightning fast – Add thousands of cells instantly
- Error-proof – No manual addition mistakes
- Flexible ranges – Sum continuous or scattered cells
- Auto-updates – Results change when source data changes
- Foundation skill – Required for almost every Excel task
The Syntax
=SUM(number1, [number2], ...)Include individual cells, ranges, or both. SUM accepts up to 255 arguments.
Example 1: Basic Range Total
Add up weekly expenses:
| Day | Amount |
|---|---|
| Monday | $45.50 |
| Tuesday | $32.75 |
| Wednesday | $58.20 |
| Thursday | $41.00 |
| Friday | $67.80 |
Formula: =SUM(B2:B6)
Result: $245.25
One formula totals all five days. Change any value and the total updates automatically.
Example 2: Multiple Ranges
Total sales from two different regions:
| Product | East | West |
|---|---|---|
| Laptop | $4,500 | $3,800 |
| Mouse | $250 | $180 |
| Keyboard | $800 | $650 |
Formula: =SUM(B2:B4, C2:C4)
Result: $10,180
SUM combines both columns into one total. All six values added together.
Example 3: Individual Cells
Add specific cells only:
| Month | Revenue |
|---|---|
| Jan | $12,500 |
| Feb | $14,200 |
| Mar | $13,800 |
| Apr | $15,600 |
| May | $16,400 |
Formula: =SUM(B2, B4, B5)
Result: $41,900
Include Jan, Mar, and Apr only. Skip Feb and May by not referencing them.
Example 4: Text and Blank Cells
What happens with mixed data?
| Item | Quantity |
|---|---|
| A | 15 |
| B | N/A |
| C | 23 |
| D | |
| E | 18 |
Formula: =SUM(B2:B6)
Result: 56
SUM ignores “N/A” and the blank cell. It only adds the three numbers: 15, 23, and 18.
Example 5: Entire Column or Row
Sum an entire column:
Formula: =SUM(B:B)
Result: Adds every number in column B
Sum an entire row:
Formula: =SUM(5:5)
Result: Adds every number in row 5
Be careful with entire columns or rows. They include everything, even cells you might not want.
Example 6: Running Total
Create a cumulative sum:
| Month | Sales | Running Total |
|---|---|---|
| Jan | $5,000 | $5,000 |
| Feb | $6,200 | $11,200 |
| Mar | $5,800 | $17,000 |
| Apr | $7,100 | $24,100 |
Formula in C2: =SUM($B$2:B2)
Formula in C3: =SUM($B$2:B3)
Copy down and the range expands automatically. The dollar signs on the first cell keep it fixed.
Quick Keyboard Shortcut
Don’t want to type the formula?
- Select the cell below your numbers
- Press Alt + = (Windows) or Command + Shift + T (Mac)
- Excel adds the SUM formula automatically
This is the fastest way to add a column or row.
Common Mistakes to Avoid
Including Headers
=SUM(B1:B6)includes the header cell=SUM(B2:B6)starts from the first number- Headers with text are ignored, but avoid them anyway
Circular References
- Don’t include the cell with the SUM formula in its own range
=SUM(B2:B10)in cell B5 creates an error- Put totals outside the range you’re summing
Hidden Rows
- SUM includes hidden rows by default
- If you filter data, SUM still counts hidden cells
- Use SUBTOTAL instead if you need to exclude hidden rows
When to Use SUM
Use SUM when:
- You need a straightforward total
- Your data is in continuous ranges
- You want automatic updates when data changes
- You’re building formulas that need totals
Don’t use SUM when:
- You need to exclude certain values (use SUMIF instead)
- You have multiple conditions (use SUMIFS instead)
- You need to ignore hidden rows (use SUBTOTAL instead)
Start Using It
Open any spreadsheet with numbers. Select a range. Type =SUM, include your cells, and press Enter. You just saved yourself from manual addition.
SUM is the first function everyone masters because it’s that essential.
Questions about SUM? Want to explore conditional summing with SUMIF? Let’s connect.