Line of Code Counter for Pasted Source Code

How to use the line of code counter

1. Paste your source code into the text area above.
2. Select the language or leave it on Auto-detect to let the tool guess based on syntax.
3. Read the breakdown of total, code, comment and blank lines immediately.
4. Check the comment ratio to see how much of the file is documentation.

How the Line of Code Counter Classifies Lines

The tool splits every line of pasted source code into one of three categories: code, comment or blank. A blank line contains only whitespace. A comment line has no executable tokens outside of a comment delimiter. Everything else is a code line, even if it also contains an inline comment.

For example, take this four-line JavaScript snippet:

// init
let x = 1; // set x

let y = 2;

The first line is a comment line. The second line has code before the //, so it counts as a code line. The third line is blank. The fourth line is code. The result is 4 total lines, 2 code lines, 1 comment line and 1 blank line. The comment ratio is 1 divided by 3 non-blank lines, which equals 33.3 percent.

Supported Languages and Comment Syntax

This code line counter has settings for eleven language groups. Selecting the correct language ensures that block comments spanning multiple lines are counted accurately.

A first line that starts with #! is counted as a comment. When auto-detect is selected, the tool looks for markers like def, func, <?php, <!DOCTYPE, #include or #!/ to pick the syntax rules, and shows which language it chose. Auto-detect is a guess, so pick the language yourself when the result looks wrong.

Why Measure Lines of Code

A lines of code counter gives a rough idea of file complexity. While raw line counts do not measure quality, they help teams track growth over time, estimate review effort and spot files that have grown too large to maintain.

The comment ratio is often more useful than the raw total. A ratio between 15 and 30 percent usually indicates reasonable documentation. Below 10 percent suggests the code may be hard for others to read. Above 50 percent sometimes means the file is mostly license headers or generated boilerplate.

If you need to measure plain text rather than source code, a general line counter is faster because it skips comment parsing entirely. For checking string length limits in APIs or forms, use a character counter instead.

Comparison With Command-Line Tools Like cloc

Command-line utilities such as cloc scan entire repositories and handle hundreds of languages. They are ideal for CI pipelines and bulk reporting. However, they require installation and terminal access.

This browser-based line counter code tool fills a different niche. It is designed for quick checks on single files or snippets without leaving your editor or opening a terminal. Because all processing happens locally in JavaScript, no source code leaves your machine. This makes it safe for proprietary or sensitive files where uploading to a server is not an option.

Strings that contain comment markers, for example let s = "// not a comment";, are handled because the parser tracks string literals before looking for comment markers. Some constructs are not parsed: raw strings in Rust and C#, PHP and shell heredocs, and the JavaScript or CSS inside an HTML page are all read with the rules of the language you selected.

Tips for Accurate Counting

To get the most reliable numbers from any code line counter, keep these points in mind:

• Select the exact language rather than relying on auto-detect when pasting short fragments that lack obvious keywords.
• Include the full file content if you want the comment ratio to reflect reality. Pasting only a function body will inflate the code percentage.
• Be aware that minified files will show almost zero blank or comment lines, which is expected but not representative of the original source.
• In Python, a triple-quoted string that starts a statement is a docstring and counts as comment lines. A triple-quoted string assigned to a variable counts as code.

Worked examples