Reference utility
Excel Column Letter ↔ Number Converter
Convert column labels such as A, Z, AA and XFD to their 1-based column numbers, or convert a number back to its Excel-style column label.
Letter → number
AA → 27
Number → letter
27 → AA
Useful for formulas and automation
Column-number conversion is handy when VBA, APIs or generated formulas use numeric indexes while humans work with A1-style labels. The converter supports the standard base-26 style used by spreadsheet columns and validates the input before returning a result.