kloc

KLOC stands for thousands of lines of code and is a software size metric used to estimate effort, productivity, and quality in software development. It expresses the size of a software artifact as the number of source code lines, typically scaled in thousands. The term is often used alongside LOC (lines of code) and SLOC (source lines of code) to reflect different counting approaches and historical estimation models such as COCOMO.

Counting methods for KLOC vary. Physical LOC counts consider each source line that contains code, with some definitions excluding comments and blank lines, while others may include certain preprocessor or template lines. Logical LOC or SLOC attempts to count statements or executable actions. Because counting depends on programming language, tooling, and counting rules, KLOC values are not directly comparable across projects or languages.

KLOC has been used to support rough estimates of effort and productivity, such as lines of code produced per person-month, and to compute defect densities per KLOC. It remains encountered in some legacy dashboards and in contexts where language- and domain-specific comparisons are appropriate. However, it has notable limitations: it does not reflect software complexity, functionality, or quality, and it can be influenced by coding style or tooling, potentially incentivizing verbose or auto-generated code.

Critics argue that KLOC is fragile, language-dependent, and prone to manipulation. Alternatives that aim to be more language- and function-agnostic include function points, use-case points, and metrics based on cyclomatic complexity or maintainability. In practice, KLOC is best used as a rough size indicator within a project, not as a sole measure of progress or quality.