In VLOOKUP, the column index number is the number that tells Excel which column (in your selected table range) to return the result from. Formula structure:

=VLOOKUP(lookup_value,texttable_array,textcol_index_num,textrange_lookup)=VLOOKUP(\text{lookup\_value},\\text{table\_array},\\text{col\_index\_num},\\text{range\_lookup})=VLOOKUP(lookup_value,texttable_array,textcol_index_num,textrange_lookup)

Here, col_index_num = column index number.

Quick Scoop: What is Column Index Number in VLOOKUP?

Think of your VLOOKUP table like a bookshelf and each column is a book from left to right.
The column index number simply says: “Bring me the value from book number X.”

  • The leftmost column of the table_array is 1.
  • The next column is 2 , then 3, 4, and so on.
  • VLOOKUP always counts within the table_array , not the whole sheet.

If your table_array is B2:D10, then:

  • Column B is 1
  • Column C is 2
  • Column D is 3

So, if you use:

=VLOOKUP(A2,\B2:D10,\3,\FALSE)

Excel will:

  1. Look for the A2 value in column B (the first column of the table_array).
  2. Return the value from the 3rd column of that range , i.e., column D.

Mini Example (Story Style)

Imagine a tiny employee table:

Column| Data
---|---
A| Employee ID
B| Name
C| Department
D| Salary

You select the table_array as A2:D100.

  • Employee ID column (A) → index 1
  • Name column (B) → index 2
  • Department (C) → index 3
  • Salary (D) → index 4

Now:

  • To get Name by ID:

=VLOOKUP("E102",\A2:D100,\2,\FALSE)

  • To get Salary by ID:

=VLOOKUP("E102",\A2:D100,\4,\FALSE)

Change the column index number, and you’re changing which field VLOOKUP returns, while the lookup value and table stay the same.

Key Things to Remember

  • Column index number starts at 1 for the leftmost column of your VLOOKUP range , not the sheet.
  • It must be between 1 and the total number of columns in your table_array; if it’s larger, VLOOKUP gives a #REF! error.
  • If your table_array is D5:G20, then:
    • D = 1
    • E = 2
    • F = 3
    • G = 4

Why Column Index Number Matters (and Common Mistakes)

If you choose the wrong column index number:

  • You’ll get the wrong field (e.g., department instead of salary).
  • Or you’ll get errors if you exceed the available columns (#REF!).

Typical mistakes:

  • Forgetting you changed the table_array and not updating the index.
  • Inserting a new column in the middle of the table, which shifts the expected column numbers and makes VLOOKUP return the wrong column.

This is why many advanced users don’t hard-code 2, 3, 4, etc., but use functions like MATCH or COLUMN to calculate the column index dynamically.

Example of Dynamic Column Index (Quick Peek)

You might see something like:

excel

=VLOOKUP($A2, $A$1:$E$100, MATCH("Salary", $A$1:$E$1, 0), FALSE)
  • MATCH("Salary", $A$1:$E$1, 0) finds which column number “Salary” is in.
  • That MATCH result is fed into VLOOKUP as the column index number.
  • If you move or insert columns, the formula still works because it recalculates the correct column position.

HTML Table: Column Index Number Cheat Sheet

Here’s a quick visual to lock it in:

Sheet Column In Table_Array A2:D10 Column Index Number Example Use in VLOOKUP
A First column of range 1 =VLOOKUP(ID, A2:D10, 1, FALSE)
B Second column of range 2 =VLOOKUP(ID, A2:D10, 2, FALSE)
C Third column of range 3 =VLOOKUP(ID, A2:D10, 3, FALSE)
D Fourth column of range 4 =VLOOKUP(ID, A2:D10, 4, FALSE)

TL;DR

  • The column index number in VLOOKUP is “which column of your selected table to return from” , counted from the left starting at 1.
  • It must stay within the width of your table_array, and choosing the right number is essential for getting the correct result.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.