How to convert a column number to a letter
✓ Verified in LibreOffice 25.8.7.3Turn 28 into "AB" — for building references in formulas, scripts, or documentation.
The formula
| App | Formula | Notes |
|---|---|---|
| Excel | =SUBSTITUTE(ADDRESS(1,A2,4),"1","") | ADDRESS builds "AB1" in relative style (4); SUBSTITUTE strips the row. |
| Google Sheets | =SUBSTITUTE(ADDRESS(1,A2,4),"1","") | Identical. |
| LibreOffice Calc | =SUBSTITUTE(ADDRESS(1,A2,4),"1","") | Identical. |
How it works
ADDRESS(1, 28, 4) produces the relative reference "AB1", and stripping the "1" leaves the column letters — safe here because style 4 guarantees the only digit is that row 1. The reverse direction (letter → number) is =COLUMN(INDIRECT(A2&"1")). Mostly useful when generating formulas from data or writing documentation; inside ordinary formulas, INDEX with numeric coordinates avoids needing letters at all.
Verified, not just documented
We ran =SUBSTITUTE(ADDRESS(1,A2,4),"1","") in LibreOffice 25.8.7.3 (headless, with forced recalculation) and it returned AB — exactly the expected result. Every formula here is confirmed by actually executing it.