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Excel Column Letter to Number List and Conversion Guide

How-to basics · Updated November 2, 2026

Excel Column Letter to Number List and Conversion Guide

Excel columns use letters, but each letter or letter combination has a number: A is 1, Z is 26, AA is 27, AB is 28, and the final column, XFD, is 16,384. To convert a column label in cell A1 to its number in Excel for Microsoft 365 on Windows, enter =COLUMN(INDIRECT(UPPER(A1)&"1")); to convert a number in A1 back to a letter, enter =SUBSTITUTE(ADDRESS(1,A1,4),"1","").

Excel column letters and their numbers

Excel numbers columns from left to right, starting at 1. The first 26 columns have one-letter labels; after Z, Excel adds another letter and continues counting. This starter list covers every one-letter column and the beginning of the two-letter sequence:

Column Number Column Number
A 1 N 14
B 2 O 15
C 3 P 16
D 4 Q 17
E 5 R 18
F 6 S 19
G 7 T 20
H 8 U 21
I 9 V 22
J 10 W 23
K 11 X 24
L 12 Y 25
M 13 Z 26

The next values continue in alphabetical order: AA = 27, AB = 28, AC = 29, and so on through AZ = 52. The next column is BA = 53. At the far end of a standard Excel worksheet, XFD = 16,384. Excel’s column labels are therefore not a fixed alphabetic code with only 26 possibilities; they are a sequence that expands to two and then three letters.

How the column-number pattern works

The sequence behaves like a base-26 counting system, except its digits represent 1 through 26 rather than 0 through 25. That difference explains why the transition is Z, AA—not Z, A0. Each letter contributes a place value: in a two-letter label, the first letter represents a group of 26 columns, and the second represents the position within that group.

For example, AB means one group of 26 plus the second letter’s value, 2, so it is column 28. For a three-letter label, each position has a larger place value: XFD is 24 × 26² + 6 × 26 + 4, which equals 16,384. The arithmetic is useful when checking an unfamiliar label, but a formula is usually quicker for everyday spreadsheet work.

Column numbers begin at 1, not 0. That is important when translating Excel references into programming indexes or matching a column number to a position in a list. In Excel, the first column is A and number 1; in some programming contexts, the first item in an array may be position 0. Do not assume those numbering systems are interchangeable.

Convert a letter to a number with a formula

For a column label stored as text in A1, this formula returns its worksheet column number:

=COLUMN(INDIRECT(UPPER(A1)&"1"))

For example, if A1 contains XFD, the result is 16,384. If A1 contains aa in lowercase, UPPER converts it to AA and the result is 27. The formula attaches the row number 1 to the label to create a reference such as AA1; INDIRECT turns that text into a reference, and COLUMN returns the reference’s column number. The row number itself does not affect the answer.

This method is convenient, but INDIRECT is a volatile function: Excel may recalculate it more often than a nonvolatile formula. It also expects a valid column label. A blank cell, extra spaces, punctuation, or a label beyond XFD can cause an error. If values come from imported data, clean or validate them before using the result in calculations.

Convert a number back to a column letter

When A1 contains a valid column number from 1 through 16,384, use:

=SUBSTITUTE(ADDRESS(1,A1,4),"1","")

If A1 contains 28, the result is AB. ADDRESS creates a cell address using row 1, the column number in A1, and reference type 4, which produces a relative address such as AB1. SUBSTITUTE removes the row digit, leaving the column label. If A1 contains 16,384, the result is XFD.

This formula is useful when a report, script, or calculation gives you a numeric index but a person needs to read the familiar Excel label. It is not a test of whether a number is in range: zero, a negative number, or a number above 16,384 is not a valid worksheet column number and may return an error or an unusable result. Add a separate check if the number comes from an external source.

Build a complete column lookup list in a worksheet

A printed list of all 16,384 columns would be unwieldy. If you need a searchable or reusable reference table, generate one in a blank worksheet instead. Put 1 in A2 and 2 in A3, select both cells, then drag the fill handle down until the sequence reaches 16,384. This creates a numeric index in column A.

With those column numbers in A2:A16385, enter this formula in B2 and fill it down alongside the numbers:

=SUBSTITUTE(ADDRESS(1,A2,4),"1","")

For example, the row where column A is 1 will show A in column B; the row where column A is 28 will show AB; and the row where column A is 16,384 will show XFD. The last worksheet row used is 16,385 because the list starts in row 2. That is well within Excel’s row limit.

In Excel for Microsoft 365 or Excel 2021, you can generate the numbers with a dynamic array instead. Enter this in A2:

=SEQUENCE(16384)

It spills the integers 1 through 16,384 down the sheet. Put the conversion formula in B2 and copy it down, or use the spilled value in A2 as the input to a corresponding conversion formula. SEQUENCE is not available in every older Excel release, so the two-seed fill method is a practical alternative when the function is missing. Before creating a full lookup, consider whether a smaller list covering only the columns your workbook uses will be easier to maintain.

Common errors and reference-style confusion

A frequent mistake is reading AA as 11 or treating it as two separate column references. It is one label for one column, and its number is 27. Another common error is assuming that the final column is IV. IV was the final column in Excel 2003; current Excel worksheets extend to XFD, which is 16,384. Older files may have been created with the earlier worksheet limit, but a current Excel worksheet uses XFD.

  • Check for extra spaces: A value such as AA is not the same text as AA for a formula that builds a reference. TRIM can remove ordinary leading and trailing spaces if needed.
  • Keep labels separate from cell references: The conversion formula expects letters such as AA, not a full address such as AA5 or $AA$5.
  • Use the correct range: A valid current Excel column number is an integer from 1 to 16,384. A decimal or out-of-range value is not a column index.
  • Know which display you are seeing: Excel’s R1C1 reference style displays columns with numbers instead of letters. On Windows, check File > Options > Formulas and the R1C1 reference style setting. This changes how references are displayed; it does not change the underlying column order.

Excel column labels are not values stored in the worksheet’s header row. A column’s letter is part of the worksheet interface, while a cell such as A1 stores its own contents. If a formula needs the position of the cell containing it, COLUMN can return that position directly; if it needs to convert text like AA, the text-to-reference approach above is appropriate.

Choosing the right conversion method

For a one-off conversion, the formula using COLUMN and INDIRECT is straightforward. For converting an index back to letters, ADDRESS with SUBSTITUTE is compact and works across many Excel versions. For a large list, a generated lookup table is easier to inspect, filter, or share than manually calculating each label.

Choose based on what the next step requires:

  • Need a number for a calculation? Convert the label to a column index, then use that number in the calculation.
  • Need a readable label in a report? Convert the numeric index back to letters.
  • Need to look up many conversions repeatedly? Build a two-column reference table and use it as a maintained lookup source.
  • Need only a quick explanation? Remember the transition points: Z = 26, AA = 27, and XFD = 16,384.

For workbooks shared with people using older versions of Excel, prefer broadly supported functions such as COLUMN, INDIRECT, ADDRESS, and SUBSTITUTE rather than relying on newer dynamic-array functions. If the workbook is only for Microsoft 365 or Excel 2021 users, SEQUENCE can make list generation faster. The conversion itself does not require a special add-in or a macro.

Frequently Asked Questions

What number is column AA in Excel?
AA is column 27. Z is 26, so AA is the first column after the 26 single-letter columns.

What is the number of Excel column XFD?
XFD is column 16,384, the last column in current Excel worksheets.

How do I convert an Excel column number to a letter?
If the number is in A1, use =SUBSTITUTE(ADDRESS(1,A1,4),"1",""). For example, 28 returns AB.

Why does Excel show numbers instead of column letters?
The workbook may be using R1C1 reference style. On Windows, review the setting under File > Options > Formulas and turn off R1C1 reference style to return to lettered column headers.

Can I make a list of every Excel column letter?
Yes. Generate the numbers 1 through 16,384 in one column, then convert each number with ADDRESS and SUBSTITUTE. A full list is usually more useful as a worksheet table than as a printed reference.

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More in How-to basics

Sources: Function behaviour and menu paths: Microsoft Support documentation for Excel. Method & sources

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