Title Capitalization Rules by Style Guide

What every style guide capitalizes

Seven rules hold in AP, APA, MLA and Chicago alike:

1. The first word of a title is capitalized.
2. The last word of a title is capitalized.
3. The first word after a colon in a title is capitalized.
4. Nouns, pronouns, verbs, adjectives and adverbs are capitalized at any length.
5. Short verbs such as "is", "are" and "be" are capitalized, because part of speech outranks length.
6. Articles ("a", "an", "the") stay lowercase inside a title.
7. Proper nouns and acronyms keep their own form.

Everything else, prepositions above all, is where the style guides part ways.

Where the style guides disagree, word by word

The four guides agree on position and on most parts of speech. They disagree on one question: how long a preposition has to be before it earns a capital. The table shows each decision on a real word.

Put a four-letter and a seven-letter preposition into one title and three different results come out. AP and APA land on the same output here, as they do for most titles.

Which small words does each style lowercase?

Three classes of small words stay lowercase inside a title: articles, coordinating conjunctions and prepositions, plus “to”. Prepositions are the only class where the guides disagree. The full word list lives in What Words Are Not Capitalized in a Title?

Articles carry no weight in any style

“A”, “an” and “the” stay lowercase in every style guide unless they open the title or the subtitle. An article carries grammar, not meaning, so no guide gives it a capital inside the title.

a room for the night → becomes A Room for the Night

Coordinating conjunctions stay lowercase

The seven coordinating conjunctions are and, but, or, nor, for, yet and so. APA's four-letter rule never reaches them, because all seven are shorter than four letters. Subordinating conjunctions such as because, if and while are capitalized in every guide.

if you build it → becomes If You Build It

Prepositions cross a length threshold

AP and APA capitalize prepositions of four letters or more; Chicago draws the line at five; MLA lowercases every preposition regardless of length. So “with” and “from” are capitalized only in AP and APA, while “about” and “between” are capitalized everywhere except MLA.

A preposition that belongs to a phrasal verb is capitalized in every style guide, because it works as part of the verb rather than as a preposition.

log in to your account → becomes Log In to Your Account

“To” stays lowercase as a preposition and as an infinitive

Inside a title, “to” is lowercase in all four guides, whether it points somewhere or marks an infinitive. Only the first and last positions give it a capital. More examples: Is “To” Capitalized in Title Case? Infinitive vs Preposition

how to write a headline → becomes How to Write a Headline

What happens at the edges of a title?

Position outranks part of speech in all four guides: no word at an edge of a title stays lowercase.

The first word is capitalized in every style

Even an article or “to” takes a capital when it opens the title.

to kill a mockingbird → becomes To Kill a Mockingbird

A subtitle after a colon restarts the rule

The first word after a colon inside a title is capitalized in all four guides, so the subtitle starts like a new title. Inside a sentence the guides disagree, which is covered in Do You Capitalize After a Colon?

title case rules: a practical guide → becomes Title Case Rules: A Practical Guide

The last word keeps its capital regardless of part of speech

A title that ends on a preposition still ends on a capital.

something to believe in → becomes Something to Believe In

How are compounds and brand names treated?

A hyphenated compound and a brand name are the two cases where a word cannot be decided as a single unit.

Hyphenated compounds split into two decisions

The first part of a compound is capitalized. The second part goes through the same small-word rule as the rest of the title: both parts of a hyphenated compound are capitalized unless the second part is an article, a short preposition or a coordinating conjunction.

self-report measures in clinical research → becomes Self-Report Measures in Clinical Research

a step-by-step guide to editing → becomes A Step-by-Step Guide to Editing

Irregular casing survives conversion

A word with a capital letter after its first position, such as iPhone or eBay, is kept exactly as typed, and acronyms such as NASA and PhD keep their form. A brand written entirely in lowercase, like adidas, carries no signal to read, so the converter capitalizes it like any other word.

iPhone tips for eBay sellers → becomes iPhone Tips for eBay Sellers

NASA grants for PhD students → becomes NASA Grants for PhD Students

The four style guides in detail

Newsrooms follow AP, psychology and the social sciences follow APA, the humanities follow MLA, and book publishers follow Chicago. Each one adds a rule the other three do not have.

AP style trades academic rules for newsroom speed

AP is the only guide of the four that treats headlines differently from the titles of books, films and songs. The full rule set is in AP Style Headlines: Capitalization Rules

AP composition titles cap words of four letters and up

For composition titles AP capitalizes every principal word, including prepositions and conjunctions of four or more letters. “With” sits exactly on that line.

AP news headlines switch to sentence case

An AP news headline capitalizes only the first word and proper nouns, and the first word after a colon is always capitalized. The converter's AP preset applies the composition-title rule; for an AP news headline, use the Sentence Case Converter instead.

Job titles lose their capital after a name

AP capitalizes a formal title before a name, as in President Lincoln, and lowercases it after the name or on its own, as in Abraham Lincoln, the president. The same logic applies to “editor in chief”. Single words such as “internet” or compass directions have their own Stylebook entries.

APA separates title case from sentence case

APA capitalizes every word of four or more letters in title case, and it is the one guide that uses both cases in the same paper: title case for headings and titles mentioned in the text, sentence case in the reference list. Details and examples: APA Title Case: Rules and Examples

Reference entries use sentence case

Titles of articles and books in an APA reference list use sentence case, while journal names keep title case. See Citing Titles in APA: Book vs Article Formatting or run the title through the Sentence Case Converter.

Self-Report Measures in Clinical Research → becomes Self-report measures in clinical research

All five heading levels use title case

All five APA 7 heading levels are written in title case. The levels differ in alignment, bold and italics, never in capitalization. The layout of each level is in Formatting Levels of Headings in APA 7

MLA capitalizes by part of speech, not length

MLA serves literature and humanities writing. It lowercases every preposition inside a title, however long, along with articles, coordinating conjunctions and “to” in infinitives, so “between” stays lowercase while “Is” is capitalized. How it compares with APA: MLA vs APA Title Capitalization

Chicago sits between AP and the academic guides

Chicago governs book publishing. Its line falls between AP's four-letter threshold and MLA's absence of one: prepositions of five or more letters are capitalized. From the 12th edition in 1969 until the 18th, Chicago lowercased prepositions regardless of length, which is why older references disagree with newer ones. More in Chicago Style Title Capitalization

Sources: AP Stylebook (entries "composition titles" and "headlines") · APA Style: title case (Publication Manual, 7th ed., section 6.17) · MLA Style Center (MLA Handbook, 9th ed.) · The Chicago Manual of Style (18th ed., section 8.158)

From rule to converted title

The title capitalization tool on this site applies exactly the rules above for the style guide you pick. Its Standard setting follows the MLA rule for prepositions.

How does the converter decide each word?

It checks each word in a fixed order and stops at the first rule that applies:

1. A known acronym is checked first, so NASA stays NASA.
2. Irregular casing is checked next, so iPhone survives.
3. The first word is capitalized.
4. The last word is capitalized.
5. The first word after a colon is capitalized.
6. “To” followed by another word is lowercased.
7. A particle that completes a phrasal verb is capitalized.
8. A hyphenated compound is split and each part decided on its own.
9. Every remaining word goes through the chosen style guide's rule.

Per-word explanations name the rule that fired

Every word the converter changes is marked in the result, with the rule behind it. The labels read like this:

• Preposition (MLA style)
• AP style: preposition with 4+ letters
• Chicago style (18th ed.): preposition with 5+ letters
• Infinitive marker stays lowercase
• First word after colon is capitalized
• Last word is always capitalized

Text pasted in ALL CAPS is normalized, not copied

In text typed entirely in capitals, the casing carries no information, so every word is rebuilt from the rules. In ordinary mixed-case text, a word in capitals is a deliberate signal and is kept.

THE MAN WHO SOLD THE WORLD → becomes The Man Who Sold the World

the NBA finals explained → becomes The NBA Finals Explained

Checking a batch of headlines against one style

Paste a list of headlines into the Batch Headline Checker, pick a style guide, and each line comes back with its fix.