Learn **how to sum every nth column** (for example, every second, third, or fifth column) using the Excel SUMCOLUMNS function.

In this tutorial, we will demonstrate how the **SUMCOLUMNS function** works. Furthermore, we will perform the task using regular **Excel functions**. The SUMCOLUMNS function allows you to sum up a specific set of columns within a range of cells.

## How to sum every nth column in Excel

Here is the formula to sum every nth column:

- Enter SUMCOLUMNS(B3:J3,3, FALSE) formula.
- Select the range of cells: B3:J3.
- Add the interval (n) to control which columns will be summed.
- Select the starting point, TRUE: first column, FALSE: “nth” column.
- The function returns the sum of every nth column.

### Syntax

`=SUMCOLUMNS(range, n = interval, [start])`

### Arguments

The function uses two required and one optional argument.

- “
**range”**is the range of cells where you search the values. - “
**interval”**is an integer (n) that identifies the column index. - “
**start**“: optional; the argument controls the starting column. In the case of TRUE, the function will start summing the columns from the first column; in the case of FALSE, every nth column will be summed.

### SUMCOLUMNS Example

In the example, you want to sum every third column starting with the 3rd column. Use FALSE as a third [optional] argument to summarize the selected range’s 3rd, 6th, and 9th columns.

**Formula:**

`=SUMCOLUMNS(B3:J3,3, FALSE)`

**Another formula with the TRUE argument:**

`=SUMCOLUMNS(B3:J3,3, TRUE)`

In this case, the function will sum up the 1st, 4th, and 7th columns.

**Implementation of the SUMCOLUMNS function:**

Press Alt + F11 to open the VBA editor. Right-click and add a new module. Finally, copy and paste the following code into your Excel Workbook:

```
Function SUMCOLUMNS(rng As Range, n As Integer, Optional start As Boolean = True)
Dim i As Integer
Dim sum As Double
sum = 0
If start = True Then
For i = 1 To rng.Columns.count Step n
sum = sum + rng.Cells(1, i).Value
Next i
Else
For i = n To rng.Columns.count Step n
sum = sum + rng.Cells(1, i).Value
Next i
End If
SUMCOLUMNS = sum
End Function
```

Now your function is ready to use.

### Sum every nth column with built-in Excel functions

Let us see the classic way; it comes with a slightly longer **formula** based on the SUM and INDEX built-in functions. The goal is the same, sum every 3rd column using a formula.

The following formula starts summing **from the first column** in the selected range.

`=SUM(INDEX(B3:J3,1,{1,4,7}))`

The formula below starts summing **from the nth column** in the selected range.

`=SUM(INDEX(B3:J3,1,{3,6,9}))`

**Related formulas:**

**Additional resources:**