Title case rules: how AP, Chicago, APA and MLA capitalize titles

Title case means capitalizing the main words of a title and leaving minor words lowercase. The major style guides agree on the core: capitalize the first and last words and all nouns, pronouns, verbs, adjectives and adverbs, and lowercase articles and short conjunctions and prepositions in the middle. They differ mainly on longer prepositions, which is why Walking with Dogs and Walking With Dogs can both be correct. The title case converter applies one consistent set of rules; this guide explains the main styles so you know which to follow.

The rules every style shares

• Capitalize the first and last words, whatever they are, so Things to Think About ends on a capital. Chicago, APA and MLA also capitalize the first word of a subtitle after a colon.
• Capitalize major words: nouns, pronouns, verbs, adjectives and adverbs, however short. That includes Is, Be, Are, It, Its, His and Not, which people often lowercase by mistake.
• Lowercase the articles a, an and the, unless they come first or last.
• Lowercase short coordinating conjunctions such as and, but, or and nor in the middle of a title.
• Capitalize phrasal-verb particles: Set Up, Log In, Give Up. Here up and in work as adverbs, not prepositions.

Where the styles differ

• AP (the Associated Press Stylebook, used by many news organisations): capitalize every word of four or more letters, including prepositions and conjunctions such as With, From, Into and Over; lowercase articles and prepositions and conjunctions of three letters or fewer unless they come first or last. These rules are for titles of works such as books, films and songs; AP's own news headlines use sentence case.
• Chicago (the Chicago Manual of Style): lowercase articles, the conjunctions and, but, for, or and nor, and the words to and as. Until its 18th edition in 2024, Chicago lowercased prepositions of any length; it now capitalizes prepositions of five or more letters, so About, Between and Through take capitals but with, from and into do not.
• APA (7th edition): capitalize all words of four letters or more, plus major words of any length, and lowercase conjunctions, articles and prepositions of three letters or fewer. In practice it lands very close to AP.
• MLA (9th edition): lowercase articles, prepositions of any length, coordinating conjunctions and the to in infinitives when they fall in the middle of a title, so through and between stay lowercase.

One title, four styles

Take the title walking with dogs through the park at night:

• AP: Walking With Dogs Through the Park at Night
• Chicago: Walking with Dogs Through the Park at Night
• APA: Walking With Dogs Through the Park at Night
• MLA: Walking with Dogs through the Park at Night

Only the prepositions with (four letters) and through (seven) change; everything else follows the shared rules, which is why learning those gets you most of the way. Pick the style your publication, teacher or client uses and apply it consistently. Mixing styles in one document is the mistake readers actually notice.

Title case or sentence case?

Sentence case capitalizes only the first word and proper nouns, like an ordinary sentence: Walking with dogs through the park at night. Many websites, apps and news outlets prefer it for headings because it is easy to read and needs no rules about small words. Style guides mix the two: APA, for example, uses title case for headings and for titles of works mentioned in the text, but sentence case for article and book titles in the reference list. Whichever you choose for a site, use it for every heading at the same level. For page titles in search results, How long should a title tag be? Pixels, not characters covers how long they should be, and the case converter switches text between sentence case, UPPER CASE and lower case.

Common mistakes

• Lowercasing short verbs and pronouns: in title case it is What Is It For, not What is it For.
• Capitalizing every word, including The, Of and And in the middle. That is start case, used in some interfaces, but it is not title case in any of these guides.
• Lowercasing the last word: Things to Think About, not Things to Think about.
• Lowercasing phrasal-verb particles: How to Set Up a Home Office.
• Breaking proper nouns and acronyms: NASA, iPhone and eBay keep their own capitalization in every style.

Converting automatically

The title case converter capitalizes the first and last words and the first word after a colon, capitalizes each part of a hyphenated compound except small words (so state-of-the-art becomes State-of-the-Art), and keeps a fixed list of small words lowercase: articles, short conjunctions, and prepositions of up to four letters such as of, with and from. That matches Chicago for those words. For AP or APA, capitalize four-letter prepositions like With and From yourself; for MLA, lowercase longer ones like through. Because it works from word lists rather than grammar, it cannot tell a preposition from a phrasal-verb particle, so check words like up and in after a verb, and while words you type with interior capitals, like NASA or iPhone, are kept as typed, an acronym typed in lowercase cannot be recognised, so check those. It also offers sentence case and start case. To test whether a headline works, not just whether it is capitalized correctly, try the headline analyzer.