Bi-directional converter between Excel column letters and column numbers using bijective base-26 positional encoding. Includes batch conversion tables and mathematical calculation breakdowns.
Runs entirely in your browser
Spreadsheets label columns with letters — A, B, … Z, then AA, AB and so on — but underneath they are just numbers, and converting between the two is a recurring need when writing formulas, macros or code that addresses cells. This tool converts a column letter to its number and a number back to its letter, in both directions, with batch support for doing many at once.
The mapping is a bijective base-26 system, which is subtly different from ordinary base-26: there is no “zero” letter, so AA is 27, not 26. That is easy to get wrong by hand, and the tool shows the calculation breakdown so you can see how a letter like XFD (the last column in modern Excel, number 16384) is derived.
It runs in your browser, so conversions are instant and private. Use it when scripting against a spreadsheet, debugging a cell reference, or generating column addresses programmatically.
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