Case Converter with APA, AP, Chicago and MLA Title Case

How to use this case converter

Paste or type your text, pick a case, and copy the result. Each line is treated as its own title, so you can convert a whole list of headings at once. Nothing is uploaded: the conversion runs in your browser and the text never leaves your device.

The plain modes (UPPERCASE, lowercase, Sentence case) and the developer modes (camelCase, snake_case, kebab-case) do what their names say. The four Title Case modes are the point of this tool: "title case" is not one rule, and style guides disagree on which small words stay lowercase.

How the four style guides differ

The same headlines, converted by each style. The differences come from two choices: whether a long preposition such as "from" is capitalized, and whether the last word is always capitalized.

The exact rules applied

• APA 7: capitalize the first word, the first word after a colon or em dash, every word of four letters or more, and all major words (nouns, verbs including short ones such as "Is" and "Be", adjectives, adverbs, pronouns). Lowercase articles, short coordinating conjunctions and short prepositions of three letters or fewer, unless they come first. Both parts of a hyphenated major word are capitalized.
• AP: capitalize words of four letters or more. Lowercase articles, conjunctions and prepositions of three letters or fewer, unless first or last.
• Chicago 17/18: lowercase articles, all prepositions regardless of length, the conjunctions and, but, for, or and nor, plus "to" and "as". Always capitalize the first and last word.
• MLA 9: lowercase articles, prepositions, coordinating conjunctions and "to". Capitalize the first and last word and the word after a colon.

Beyond the style rules, the converter keeps all-caps acronyms (NASA, HTML), words with internal capitals (iPhone, JavaScript), URLs and email addresses exactly as typed. Spacing and punctuation are preserved, apostrophes are handled ("don't" becomes "Don't", "rock 'n' roll" becomes "Rock 'n' Roll"), and in hyphenated compounds the first and last parts are capitalized while middle minor words stay lowercase ("Up-to-Date", "State-of-the-Art"). Chicago adds one rule (17th edition, 8.161): after a prefix that is not a word on its own, such as anti-, pre-, non- or re-, the next part stays lowercase unless it is a proper noun, so Chicago gives "Anti-inflammatory" and "Non-English" while the other styles give "Anti-Inflammatory". The colon and em dash start a new clause in every title style, and AP and Chicago also capitalize the last word, as the rules above state.

Limitations

The tool has no part-of-speech tagger, so it decides by word list. Some words are ambiguous: "up", "down", "out", "off", "over" and "past" can be adverbs or prepositions. The converter treats them as prepositions only when they are followed by a word such as "to", "the" or "of", and as adverbs otherwise, which is the most common reading but not always the right one ("Look Up the Word" will come out as "Look up the Word"). Likewise "for", "as" and "so" can be conjunctions or prepositions, and "like" or "since" can be several things. Verbs and adjectives that look like short function words are not distinguished from them either. Treat the result as a very good first pass and check the edge cases yourself.

An all-caps line of two or more words is treated as shouting rather than a list of acronyms, so "THE QUICK BROWN FOX" becomes "The Quick Brown Fox". In a mixed line, words typed in all caps are kept as acronyms. Where a style guide has a rule the tool cannot see, such as proper names, species names or a publisher's house style, the guide itself wins.

Style editions change, and journals and publishers add their own exceptions, so if you are submitting work, confirm the rule in the current edition of the guide you are following.