Case Converter — Change Text to Upper, Lower, Title & Sentence Case

This free case converter instantly changes text between uppercase, lowercase, title case, sentence case, and developer formats like camelCase, snake_case, and kebab-case. Title case capitalises the principal words while leaving short articles and prepositions lowercase, whereas sentence case capitalises only the first word and proper nouns — rules that vary between the AP and Chicago style guides. Paste any text and switch instantly. Everything runs in your browser, so your content is never uploaded, and there are no length limits.

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✨ Pro Tips for Best Results

  • Title Case vs AP Style: Note that this tool capitalizes every word. AP and Chicago styles keep small words (like "the", "of") lowercase unless they are the first or last word.
  • Clean Before Converting: Use the "Clear" button to ensure no invisible trailing spaces are included in your transformation.
  • URL Friendly: Use kebab-case if you are creating file names or URL slugs to ensure maximum compatibility.

Developer Case Styles: When to use what?

In programming, case styles are used to distinguish between variables, classes, and constants:

  • camelCase: Standard for JavaScript variables and functions (e.g. userFirstName).
  • snake_case: Common in Python and database field names (e.g. user_first_name).
  • kebab-case: Used for CSS classes and URL slugs (e.g. user-first-name).
  • PascalCase: (Capitalized camelCase) Used for Classes in most languages (e.g. UserAccount).

How case conversion works

This tool converts text between four common case styles: UPPER CASE, lower case, Title Case, and Sentence case. Each conversion is handled differently in JavaScript to account for the nuances of each style.

UPPER CASE: All characters converted to uppercase via toUpperCase().
lower case: All characters converted to lowercase via toLowerCase().
Title Case: The first letter of each word is capitalised, the rest lowercased. Words are split on whitespace.
Sentence case: Only the first letter of the first word in each sentence is capitalised. Sentence boundaries are detected at . ! ? followed by a space or line break.

Note that Title Case here capitalises every word including short prepositions and articles (a, an, the, of, in). Formal title case style (AP, Chicago, APA) has more complex rules that keep small words lowercase — use this for general-purpose conversion, and apply style-guide rules manually for formal publications.

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Title case vs sentence case

Sentence case capitalises only the first letter and proper nouns — the natural style for body text and increasingly for headlines too. Title case capitalises the principal words but leaves short articles, conjunctions and prepositions (a, an, the, and, of, in) lowercase unless they start the line. The exact rules differ between the AP, Chicago and APA style guides, which is why automated title-casing sometimes disagrees with a given style sheet.

The other cases and where they're used

Watch the edge cases

Acronyms (NASA, API), hyphenated words and names like "McDonald" or "O'Brien" defeat naive capitalisation. Always proofread converted headings — no algorithm fully captures every style guide's exceptions, so treat the output as a fast first pass.

⚠️ Common Mistakes to Avoid

Frequently asked questions

What is Sentence Case?

Sentence case capitalizes only the first letter of the first word and any proper nouns, just like a standard sentence.

Can I convert large blocks of text?

Yes, our tool handles everything from single words to multi-page documents instantly.

Reviewed by the ToolsmithPro editorial team · Last updated June 2026. Every calculation and conversion runs entirely in your browser — your inputs are never uploaded, stored or shared. Formulas and methodology are documented on our about page; spot an error? tell us and we'll fix it.