To sum the last n columns in a table of data (i.e. last 3 columns, last 4 columns, etc.) you can use a formula based on the INDEX function. In the example shown, the formula in K5:


where "data" is the named range C5:H8

Generic formula



The key to understanding this formula is to realize that the INDEX function can be used to return a reference to entire rows and entire columns.

To generate a reference to the "last n columns" in a table, we build a reference in two parts, joined by the range operator. To get a reference to the left column, we use:


Since data contains 6 columns, and K4 contains 3, this simplifies to:

INDEX(data,0,4) // all of column 4

To get a reference to the right column in the range, we use:


Which returns a reference to column 6 of the named range "data", since the COLUMN function returns 6:

INDEX(data,0,6) // all of column 6

Together, the two INDEX functions return a reference to columns 4 through 6 in the data (i.e. F5:H8), which resolve to an array of values inside the SUM function:


The SUM function then calculates and returns the sum, 135.

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Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.