Convert the name of an Excel column to a number

Read a column name as a base-26 number where A is 1.

JavaScript Version 1.0.0 · MIT · .md

function columnNumber(column) { return column.split('').reduce((total, letter) => total * 26 + parseInt(letter, 36) - 9, 0); }

Input & expected output

"AB"

28

The edge case

"a"

1

Know the limits

• The lab accepts 1–6 letters (up to ZZZZZZ). Lowercase letters work too.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Capitalize a string — Uppercase the first Unicode code point and preserve the remaining text.
• Reverse a string — Reverse Unicode code points without splitting surrogate pairs.
• Check a palindrome — Compare a string with its code-point reversal.