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Title Case Converter (AP, APA, Chicago)

Capitalize a headline the way AP, APA, Chicago or MLA actually prescribe, and see all four versions side by side so you can tell where the styles disagree.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Type or paste the headline you want to set in title case.
  2. 2.Choose the style guide your publication follows: AP, APA, Chicago or MLA.
  3. 3.Copy the converted headline, or compare the four style outputs listed underneath before deciding.

About Title Case Converter (AP, APA, Chicago)

Title Case Converter capitalizes a headline according to a real editorial style guide rather than a generic capitalize-every-word rule. Type or paste a title, choose AP, APA, Chicago or MLA, and the page returns the correctly cased headline together with the other three versions so you can see exactly where the guides disagree. That comparison is the point: the same eight-word headline can be set four different ways depending on which manual your publication follows, and the difference usually comes down to short words.

All four styles agree on the two anchors: the first word and the last word of a title are always capitalized, whatever they are. They differ on everything in between. AP capitalizes words of four or more letters and lowercases articles, coordinating conjunctions and prepositions of three letters or fewer. APA 7th edition uses the same four-letter threshold, capitalizes both parts of a hyphenated major word, and capitalizes the first word after a colon. Chicago changed in the 18th edition, published in 2024: it no longer lowercases prepositions regardless of length, and now capitalizes prepositions of five or more letters while keeping shorter ones down. MLA 9th edition still lowercases articles, prepositions and coordinating conjunctions no matter how long they are, along with the infinitive to. A title such as a phrase built around a five-letter preposition is therefore set differently by Chicago and MLA, which is precisely the case a generic converter gets wrong.

The converter is a deterministic word-list matcher, and it is honest about what that means. It does not tag parts of speech, so a word that appears on the preposition list is treated as a preposition even when it is acting as an adverb or a verb particle in your sentence. If you need a particular word forced up, type it with an internal capital: any word you enter in full capitals of two letters or more, or with a capital letter inside it, passes through untouched. That is how acronyms and product names such as NASA, HTML5 and iPhone survive conversion instead of being flattened into Nasa and Iphone. A headline pasted entirely in capitals is the one exception: there is nothing in ALL CAPS text that separates an acronym from a shouted word, so the whole line is lowercased first and then cased normally, which is what you want when you paste a screaming headline out of a CMS. Two other limits follow from having no grammar parser: MLA capitalizes a word such as before when it introduces a clause but lowercases the same word as a preposition, and AP has capitalized the to of an infinitive since 2019. Neither is detected here, so capitalize those by hand. Punctuation, spacing and word order are never altered; only letter case changes.

Every rule and word list in the tool is taken from a published source rather than from memory, and the sources are listed on this page so you can check them. The APA and MLA rules come from those organizations' own style pages, and the Chicago behavior comes from the Chicago Manual of Style's own account of the 18th edition change. AP's composition-title rule is drawn from secondary sources that quote the AP entry, because the AP Stylebook itself is behind a subscription; that is stated plainly rather than glossed over, and it means AP is the one style here that could not be checked against a first-hand source.

Everything runs in your browser, so nothing you type is uploaded, stored or attached to an account. This is a different job from a plain case converter, which mechanically produces uppercase, lowercase or capitalized-every-word output without any editorial rules. Use this one when a house style is involved: headlines, article titles, book and film titles, reference lists, slide decks and anything that will be copy-edited.

Methodology & sources

Tokenize the title while preserving punctuation and spacing, classify each word against style-guide article, conjunction and preposition lists taken from published sources, then apply the selected style's length threshold plus the first word, last word, post-colon and hyphenated-compound exceptions.

Frequently asked questions

Why do Chicago and MLA give me different results?
Chicago's 18th edition now capitalizes prepositions of five or more letters, while MLA 9 still lowercases prepositions no matter how long they are. Long prepositions are where the two styles part company.
I pasted an ALL-CAPS headline and it stayed the same. Why?
It should not any more: a title with no lowercase letter at all is lowercased before casing. Within a mixed-case title, words in full capitals such as NASA or FBI are still preserved, because there they are unambiguously acronyms.
Is this the same as the site's case converter?
No. The case converter applies mechanical transformations such as UPPERCASE and camelCase. This tool applies published editorial capitalization rules, including first and last word exceptions and small-word lists.

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