How to use the Excel Column Letter Converter tool
- Type column letters such as AB in the first box to see the column number.
- Type a number from 1 to 16384 in the second box to see its letters.
- Type a cell address such as B12, $C$7 or BC105 to see its column and row, plus the R1C1 form.
- Use the quick reference table for common boundaries such as Z, AZ and ZZ.
Worked example: AB, column 2000 and BC105
Three questions that come up when writing formulas, macros or import scripts:
- Column AB is number 28: A counts 1 x 26, then B adds 2, so 26 + 2 = 28.
- Column number 2000 is BXX. Check: B is 2, so 2 x 676 = 1352; X is 24, so 24 x 26 = 624; the last X adds 24. 1352 + 624 + 24 = 2000.
- Cell BC105 is column 55, row 105, which is R105C55 in R1C1 style.
The last column Excel allows, XFD, is 16384.
How column letters work
Excel columns count like a number system with 26 digits, A to Z, but with no zero. After Z comes AA, after AZ comes BA, and after ZZ (702) comes AAA (703). To turn letters into a number, take each letter’s position in the alphabet, multiply the running total by 26 and add the next letter. To go the other way, the tool repeatedly divides by 26, which is the same method used by spreadsheet libraries. Since Excel 2007 a sheet can have 16,384 columns and 1,048,576 rows; older .xls files stopped at column IV, number 256.
When you need it
Column numbers are what VBA, Python libraries, Google Apps Script and many import tools use, while people read letters. The converter helps when a script reports an error in column 37 and you need to find AK, when you write a formula with INDEX or OFFSET, or when you map CSV fields to spreadsheet columns. Addresses with dollar signs, used for absolute references, are understood, and invalid input is explained in plain words.
Your files stay on your device
The conversion is simple arithmetic done instantly by code in this page. Nothing you type is sent anywhere or stored.
Frequently asked questions
What number is column AA?
AA is column 27. Z is 26, so AA is the first two-letter column.
What is the last column in Excel?
XFD, which is column 16,384. Rows go up to 1,048,576.
How do I convert a column number to letters in a formula?
In Excel you can use =SUBSTITUTE(ADDRESS(1,28,4),"1","") which returns AB. This page gives the answer without a formula.
Does it accept lower case letters?
Yes. ab and AB both give 28.
What does R1C1 mean?
It is an alternative addressing style that names the row and column by number, so BC105 becomes R105C55.