snake_case vs kebab-case: Which to Use?
Published 2026-02-13 · convertcase.in
Both snake_case and kebab-case use separators between words, but they differ in separator character and context. Here's a clear breakdown.
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1Separator Difference
snake_case: underscores (my_file_name) kebab-case: hyphens (my-file-name)
2Where Each Is Used
snake_case: Python, databases, file names (Linux), environment variables. kebab-case: URLs, CSS class names, HTML attributes, NPM packages.
3URLs: Always kebab-case
Google recommends hyphens in URLs: /convert-case-tool (not /convert_case_tool). Hyphens are treated as word separators; underscores are not.
Frequently Asked Questions
Should CSS class names use snake_case or kebab-case?
kebab-case is the conventional choice for CSS: .btn-primary, .card-header. It matches URL conventions and is easier to read.