Add Line Numbers Tool

About this calculator

This tool splits pasted text at each line break and prefixes every line with a sequential number, formatted consistently (with padding and a chosen separator) so the numbering stays aligned even as line lengths vary — a plain-text equivalent of what code editors show in their gutter or what word processors do with automatic line numbering.

Programmers preparing code snippets for documentation or bug reports, teachers numbering worksheet lines, and legal or manuscript editors who need to reference specific lines in a document use it to add numbering without opening a full editor — useful whenever you need to say “see line 42” in a plain-text file that doesn't have built-in line numbers.