Lines of Code (LOC) is a software metric measuring program size by counting source code lines — used for effort estimation, productivity measurement, and codebase analysis, though controversial as a quality indicator.

What Is LOC?

• Definition: Count of source code lines in a program.
• Variants: SLOC (source), LLOC (logical), CLOC (comment), BLOC (blank).
• Use: Size estimation, productivity metrics, complexity indicators.
• Tools: cloc, sloccount, tokei, wc -l.
• Context: Code AI uses LOC for context window management.

Why LOC Matters

• Estimation: Correlates with development effort.
• Comparison: Benchmark codebase sizes across projects.
• Complexity Proxy: Larger code often means more complexity.
• Code AI: Determines how much context fits in LLM window.
• Technical Debt: Track growth over time.

LOC Counting Methods

• Physical LOC: Actual lines including blanks.
• Logical LOC: Statements (semicolons in C-like languages).
• Comment Lines: Documentation density.
• Blank Lines: Code formatting style.

Limitations

• Language differences (Python vs Java verbosity).
• Quality not measured (bad code can be short or long).
• Incentivizes verbose code if used for productivity.

LOC is useful for sizing, not quality — a starting point for codebase understanding.