To convert to title case online with editorial accuracy, apply a named publication style rather than a rule that capitalizes every word. The Title Case Converter (AP, APA, Chicago) runs in your browser and returns four versions of the same headline: AP, APA 7, Chicago CMOS 18 and MLA 9. That side-by-side result matters because the manuals do not always agree on which words deserve a capital. All four versions capitalize the first and last word, but their treatment of intermediate articles, conjunctions and prepositions can differ, especially when a preposition is five letters or longer. You can paste a draft headline, choose the guide followed by your publication, and copy the version you need. You can also inspect the other three outputs before deciding, which helps when a style guide is not specified or when you want to understand an editorial difference before sending copy to an editor. The converter follows published word lists and style rules rather than a generic “title case” preset. It changes letter case without changing punctuation, spacing or word order. It also preserves mixed-case brand names and acronyms such as iPhone, HTML5 and NASA, although an entirely uppercase line is treated differently because the tool cannot know which all-capital words are acronyms. In short, it is built for setting a headline under a named house style, not for mechanically changing every word.
What the converter actually changes
The converter tokenizes the title while preserving punctuation and spacing. It classifies words against article, conjunction and preposition lists drawn from published sources, then applies the selected style’s length threshold along with its relevant first-word, last-word, post-colon and hyphenated-compound exceptions. This makes the process a deterministic word-list matcher, not a grammatical interpretation of the sentence. That design explains both its consistency and its boundaries: it applies the listed rule to each word, but it does not inspect how that word functions in context. Punctuation, spacing and word order are never altered; only letter case changes.
| Style | Relevant capitalization rule | Distinctive treatment to check |
|---|---|---|
| AP | Words of four or more letters are capitalized. | Articles, coordinating conjunctions and prepositions of three letters or fewer stay lowercase. |
| APA 7 | It uses the same four-letter threshold. | Both parts of a hyphenated major word and the first word after a colon are capitalized. |
| Chicago CMOS 18 | Prepositions of five or more letters are capitalized. | Shorter prepositions stay lowercase, unlike the blanket treatment used by the previous edition. |
| MLA 9 | Prepositions are not capitalized. | Articles, prepositions, coordinating conjunctions and the infinitive “to” stay lowercase regardless of length. |
These are the relevant differences rather than a complete reproduction of every manual. All four styles always capitalize the first and last words, even when one of those words would ordinarily be lowercase as an article or preposition. The table focuses on rules likely to cause visible disagreement when you compare the four outputs.
Set a headline in the required style
- Type or paste the headline you want to set in title case into the converter.
- Choose the style guide your publication follows: AP, APA, Chicago or MLA.
- Copy the converted headline, or compare the four style outputs listed underneath and choose the version that matches your target.
Choose the style that matches your publication rather than judging only by the first line. Once a style is selected, the page presents the correctly cased headline and the other three versions underneath it. Comparing those versions is useful for two common editorial tasks: checking a title against a known house style and seeing exactly which small word caused two otherwise similar headlines to diverge. Copy after making that decision.
Why the four guides disagree
For example, consider A Guide for Learning About Modern Historical Events. AP, APA 7 and Chicago CMOS 18 render it as A Guide for Learning About Modern Historical Events. MLA 9 renders it as A Guide for Learning about Modern Historical Events. The visible disagreement comes from “about”: Chicago now capitalizes prepositions of five or more letters, while MLA continues to lowercase prepositions regardless of length. The shorter preposition “for” remains lowercase under all four approaches. A generic converter that capitalizes every word misses the editorial decision entirely; a generic title-case preset may also apply one style’s rules when the publication requires another.
The rules are grounded in published material. The APA and MLA rules come from those organizations’ own style pages. The converter follows APA Style’s title-case guidance and the Chicago Manual of Style’s account of the 18th edition change. Every rule and word list is taken from a published source, and the source notes are available on the tool’s page so you can check them. AP is the one exception in the sourcing: because the AP Stylebook sits behind a subscription, the composition-title rule is drawn from secondary sources that quote the AP entry. The tool states that limitation rather than implying that its AP result was checked against a first-hand copy of the manual.
Keep acronyms and product names intact
Proper names are one of the most common reasons a headline needs more than automatic capitalization. In a mixed-case title, any word entered in full capitals with two or more letters passes through untouched. A word with an internal capital also passes through, which protects forms such as iPhone and HTML5, as well as NASA and FBI. You do not need to remove genuine capitals before pasting the headline.
A completely uppercase input is different. If a title contains no lowercase letter at all, the converter lowercases the whole line before applying the normal rules. This removes a shouted CMS headline, but it also means an all-capital acronym cannot be identified from the pasted line by itself. For example, a line consisting only of “NASA” will not remain all capitals after that normalization. In a mixed-case headline, NASA and other full-capital words remain distinguishable and are preserved. Review the converted line if the entire input was in capitals.
Handle context-dependent capitalization
The converter does not tag parts of speech. If a word appears on a style guide’s preposition list, the matcher treats it as a preposition even when the sentence uses it as an adverb or a verb particle. That is the trade-off of a deterministic list-based tool, and it means a final editorial check remains important.
- MLA capitalizes “before” when it introduces a clause but lowercases it when it serves as a preposition. The converter cannot detect that distinction, so check the word in context.
- AP has capitalized the “to” in an infinitive since 2019. The converter does not infer that grammatical use, so correct that case by hand when needed.
The selected guide still supplies the baseline. APA 7, for example, automatically capitalizes both parts of a hyphenated major word and the first word after a colon. Those rules do not authorize the converter to rewrite the headline; punctuation and word order stay as entered, and only the affected letters change.
Check the result against your publication
This tool fits headlines, article titles, book and film titles, reference lists, slide decks and other copy that will be edited against a house style, provided the required job is capitalization. A plain case converter performs mechanical transformations such as uppercase, lowercase or capitalized-every-word output; it does not decide which small words a named editorial guide keeps lowercase. The Title Case Converter is the appropriate choice when a publication style governs the work.
Everything runs in your browser, so nothing you type is uploaded, stored or attached to an account. Before copying the final version, use a short review:
- Confirm that you selected AP, APA 7, Chicago CMOS 18 or MLA 9.
- Compare all four outputs when the publication has not specified a guide or when you are checking how another style would read.
- Check acronyms, product names and context-sensitive words such as “before” or an infinitive “to.”
- Make sure the headline still has the punctuation, spacing and word order you intended.
When the same title can produce four defensible versions, the side-by-side view turns capitalization from guesswork into a concrete editorial choice. Paste the draft, select the required guide, review the comparison and copy the version that matches the publication.