Add Line Numbers
About This Line Numberer
This line numberer adds sequential numbers to the beginning of each line in any text you provide. It runs entirely in your browser — no data is sent to a server.
Line numbers are essential when you need to reference specific locations in text. "See line 14" is precise; "the part near the middle" is not. That precision matters in code reviews, legal citations, poetry analysis, and collaborative editing.
How to Use It
- Paste your text into the input field above
- Choose your format — separator, padding, and starting number
- Copy the output — numbered text updates instantly as you type
Options Explained
- Start at: Set the first line number. Default is 1. Use 0 for array-style numbering, or a higher number for document continuations (e.g., start at 51 for the second half of a file).
- Separator: Character(s) between the number and text. Colon works for general use, tab for code, period for prose, pipe for log files.
- Padding: Keeps numbers aligned in longer texts. Space padding right-aligns numbers (common for code). Zero-padding prepends zeros (good for fixed-width output). No padding is fine for texts under 10 lines.
- Skip empty lines: Don't assign numbers to blank lines. Useful for poetry (stanza breaks) or prose (paragraph gaps).
- Right-align numbers: Numbers align to the right so text starts at a consistent column. Recommended for anything over 9 lines.
Common Use Cases
- Code snippets — for documentation, tutorials, or code review discussions
- Poetry and lyrics — literary analysis cites specific line numbers
- Legal text — courts often require numbered lines on pleadings and transcripts
- Log files — debugging is faster when you can say "error at line 847"
- Academic manuscripts — peer reviewers reference lines in their feedback
- Scripts and screenplays — directors and actors coordinate by line number
Formatting Tips
- For code: Tab separator + space padding + right-align for a clean, IDE-like look
- For prose: Period separator + space padding for readable citations
- For log files: Pipe separator + zero-padding for consistent column width
- For quick reference: Colon separator + no padding when brevity matters
For a deeper guide on line numbering conventions across different fields, see How to Add Line Numbers to Text.
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are estimates and may vary based on actual conditions.
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Line Numberer FAQ
What is a line numberer?
A line numberer is a tool that adds sequential numbers to the beginning of each line in a block of text. You paste your text, choose a separator and formatting style, and the tool outputs each line prefixed with its number. It's commonly used for code snippets, legal documents, poetry analysis, and log files.
How do I add line numbers to text online?
Paste your text into the input field, choose a separator (colon, period, tab, or pipe), select a padding style (none, spaces, or zeros), and optionally set a custom starting number. The numbered output updates instantly as you type. Click Copy to copy the result.
Is my text sent to a server?
No. This line numberer runs entirely in your browser using JavaScript. No text is uploaded to any server. When you close or refresh the page, your input is gone.
What separator should I use between line numbers and text?
Use a tab for code (matches IDE conventions), a colon and space for general purpose, a period and space for prose and legal text, or a pipe for log files. The most important rule is to stay consistent within a single document.
How do I keep line numbers aligned in long texts?
Use padding. Right-aligned space padding is the most common choice for code. Zero-padding (01, 02, …, 99) works well for fixed-width output and file sorting. Without padding, numbers shift the text when the digit count changes (1 vs. 10 vs. 100).
Should I number empty lines or skip them?
Number all lines when physical line position matters (code, log files, legal text). Skip empty lines when they are just formatting separators, such as blank lines between stanzas in poetry or between paragraphs in prose.
Can I start numbering from a number other than 1?
Yes. Set the 'Start at' field to any number. This is useful when you're numbering a continuation — for example, lines 51–100 of a longer document, or when you need 0-based numbering for array references.
What are common uses for line numbers?
Common uses include code reviews and documentation (referencing specific lines), legal filings (courts often require numbered lines), poetry and literary analysis (citing lines by number), log file debugging, screenplay rehearsal, and academic peer review.