Excel Column Number Converter
Turn a column letter into its number and back. A is 1, AA is 27, and the last column XFD is 16384.
Built for the moment a formula or a macro needs the number of a column instead of its letter. Enter letters to get numbers, or numbers to get letters. A range like A:D is counted for you, and a cell address like B3 converts to R1C1 notation. Paste many lines at once. Nothing you enter leaves this screen.
One entry per line. The letter side reads A, A:D and B3. The number side reads 27 and 1:4. The notation side turns B3 into R3C2, and R3C2 back into B3.
The limits of one worksheet
A worksheet holds 16,384 columns, A through XFD, and 1,048,576 rows. Those are the figures in Microsoft's own specification. Anything outside that range is reported as unreadable rather than guessed at.
XFD = 16,384
Nothing you entered was sent anywhere. Everything was calculated on this screen.
Column letters are not ordinary base 26
Z is followed by AA, not BA, because each digit runs from 1 to 26 rather than from 0 to 25. Short conversion snippets go wrong at exactly that point, so this converter round-trips every column from 1 to 16,384 and confirms that none of them drift before shipping.
Sources
How Excel counts column letters and numbersMade alongside
Other services by the same maker.