Reference guide

Capitalization Rules by Style Guide

Compare how AP, APA, MLA, Chicago, and standard title case handle prepositions, conjunctions, articles, and other tricky words — with a side-by-side table and real examples.

Active style focus: MLA style guidance

Style Guide Overview

Associated Press Stylebook

The AP Stylebook is the primary reference for journalists, newsrooms, and digital media. It favors readability and consistency in headline casing, capitalizing longer prepositions while keeping short function words lowercase.

—Capitalize words with 5 or more letters, including prepositions and conjunctions
—Lowercase articles (a, an, the) in middle positions
—Always capitalize the first and last word of the title
—Capitalize both parts of hyphenated compounds in most cases

Source: AP Stylebook (56th Edition (2024))

APA Publication Manual

The APA Publication Manual is the standard for academic and scientific writing. Its title case rules capitalize words of four or more letters, creating a slightly more capitalized look than AP style.

—Capitalize words with 4 or more letters, including prepositions and conjunctions
—Lowercase short conjunctions (and, but, or, nor, yet, so, for) under 4 letters
—Lowercase short prepositions (at, by, in, of, on, to, up) under 4 letters
—Always capitalize the first word after a colon, dash, or end punctuation

Source: APA Style (7th Edition (2019))

MLA Handbook

The MLA Handbook serves humanities scholars and literature students. Its title case conventions are close to Chicago style, keeping most prepositions and conjunctions lowercase regardless of length.

—Capitalize the first and last word of the title and subtitle
—Lowercase articles, prepositions, and coordinating conjunctions in middle positions
—Capitalize all other words, including long prepositions like "between" or "through"
—Capitalize the first word after a colon

Source: MLA Handbook (9th Edition (2021))

The Chicago Manual of Style

The Chicago Manual of Style is the gold standard for book publishing and formal editorial work. It uses a traditional approach that lowercases most prepositions and conjunctions in middle positions.

—Lowercase articles (a, an, the) in middle positions
—Lowercase coordinating conjunctions (and, but, or, nor, yet, so, for)
—Lowercase prepositions in middle positions regardless of length
—Always capitalize the first and last word of title and subtitle

Source: Chicago Manual of Style (17th Edition (2017))

Standard Title Case

Standard title case is a balanced default used when no specific style guide is required. It follows broadly accepted conventions: capitalizing major words while lowercasing most short function words in middle positions.

—Capitalize major words (nouns, verbs, adjectives, adverbs)
—Lowercase articles, short prepositions, and short conjunctions in middle positions
—Always capitalize the first and last word
—Capitalize words after colons and major punctuation

Source: Title Case Converter (General convention)

Style Comparison Table

How each style treats the same input. Differences are where editorial consistency matters most.

Scenario	Standard	AP	APA	MLA	CHICAGO
Long preposition: "across" (6 letters) AP and APA capitalize "across" (5+ and 4+ letters). Standard, MLA, and Chicago keep it lowercase.	Running across the Bridge at Night	Running Across the Bridge at Night	Running Across the Bridge at Night	Running across the Bridge at Night	Running across the Bridge at Night
Long preposition: "between" (7 letters) Despite its length, only AP and APA capitalize "between". Chicago and MLA keep all prepositions lowercase.	The Cat Is between the Boxes	The Cat Is Between the Boxes	The Cat Is Between the Boxes	The Cat Is between the Boxes	The Cat Is between the Boxes
Short preposition: "with" (4 letters) Only APA capitalizes "with" (4+ letter threshold). All other styles keep it lowercase.	Writing with Confidence and Purpose	Writing with Confidence and Purpose	Writing With Confidence and Purpose	Writing with Confidence and Purpose	Writing with Confidence and Purpose
Short preposition: "from" (4 letters) APA capitalizes both "from" (4 letters) and "around" (6 letters). AP capitalizes only "around" (5+ letters).	Ideas from around the World	Ideas from Around the World	Ideas From Around the World	Ideas from around the World	Ideas from around the World
Subtitle after colon All styles agree: the first word after a colon is always capitalized, even articles like "a".	Title Case Rules: A Practical Guide	Title Case Rules: A Practical Guide	Title Case Rules: A Practical Guide	Title Case Rules: A Practical Guide	Title Case Rules: A Practical Guide
Preposition "about" (5 letters) AP capitalizes "about" at exactly 5 letters (its threshold). APA does too (4+ letters).	The Rules about Writing and Thinking	The Rules About Writing and Thinking	The Rules About Writing and Thinking	The Rules about Writing and Thinking	The Rules about Writing and Thinking
Preposition "after" (5 letters) "Along" is capitalized by all styles (5+ letters), but "after" splits AP/APA from the rest.	She Walked Along the River after Lunch	She Walked Along the River After Lunch	She Walked Along the River After Lunch	She Walked Along the River after Lunch	She Walked Along the River after Lunch

Common Edge Cases

Short connectors and prepositions

Input: walking during the light

Current style (mla): Walking during the Light

Compare all styles

Standard: Walking during the Light
AP: Walking During the Light
APA: Walking During the Light
MLA: Walking during the Light
CHICAGO: Walking during the Light

The word 'during' changes across styles and is a common source of editorial inconsistency.

Subtitle after colon

Input: title case rules: a practical guide for editors

Current style (mla): Title Case Rules: A Practical Guide for Editors

Compare all styles

Standard: Title Case Rules: A Practical Guide for Editors
AP: Title Case Rules: A Practical Guide for Editors
APA: Title Case Rules: A Practical Guide for Editors
MLA: Title Case Rules: A Practical Guide for Editors
CHICAGO: Title Case Rules: A Practical Guide for Editors

Subtitles should start clearly after punctuation so the user has a reliable next edit decision.

Hyphenated and branded wording

Input: state-of-the-art workflows for iPhone launches

Current style (mla): State-of-the-Art Workflows for iPhone Launches

Compare all styles

Standard: State-of-the-Art Workflows for iPhone Launches
AP: State-of-the-Art Workflows for iPhone Launches
APA: State-of-the-Art Workflows for iPhone Launches
MLA: State-of-the-Art Workflows for iPhone Launches
CHICAGO: State-of-the-Art Workflows for iPhone Launches

Hyphenation and brand casing are frequent edge cases where users should verify output quickly before publishing.

Infinitive "to" vs preposition "to"

Input: to be or not to be

Current style (mla): To Be or Not to Be

Compare all styles

Standard: To Be or Not to Be
AP: To Be or Not to Be
APA: To Be or Not to Be
MLA: To Be or Not to Be
CHICAGO: To Be or Not to Be

"To" as the first word is always capitalized. In middle positions, all styles lowercase it whether used as an infinitive marker or preposition.

Short verb "is" in the middle

Input: she is an editor-in-chief

Current style (mla): She Is an Editor-in-Chief

Compare all styles

Standard: She Is an Editor-in-Chief
AP: She Is an Editor-in-Chief
APA: She Is an Editor-in-Chief
MLA: She Is an Editor-in-Chief
CHICAGO: She Is an Editor-in-Chief

"Is" is a verb, not a preposition or conjunction, so all styles capitalize it. Many writers mistakenly lowercase short verbs.

4-letter preposition "with"

Input: writing with confidence and purpose

Current style (mla): Writing with Confidence and Purpose

Compare all styles

Standard: Writing with Confidence and Purpose
AP: Writing with Confidence and Purpose
APA: Writing With Confidence and Purpose
MLA: Writing with Confidence and Purpose
CHICAGO: Writing with Confidence and Purpose

APA's 4-letter threshold uniquely capitalizes "with" — the only style to do so. This is one of the most common APA-specific differences.

Frequently Asked Questions

Which capitalization style should I use?

Use the style required by your publication or institution. AP style is standard for journalism and news, APA for academic and scientific papers, MLA for humanities essays, and Chicago for book publishing and formal editorial work.

What is the main difference between AP and Chicago title case?

The key difference is how they treat longer prepositions. AP capitalizes prepositions with 5 or more letters (like "Between" and "Through"), while Chicago keeps all prepositions lowercase in middle positions regardless of length.

Should I capitalize "is" in a title?

Yes. "Is" is a verb (a form of "to be"), and all major styles agree that verbs should always be capitalized in titles, even short ones.

Are there words that are always lowercase in titles?

No word is always lowercase. Even articles like "a", "an", and "the" are capitalized when they appear as the first or last word of a title. In middle positions, articles, short prepositions, and short conjunctions are typically lowercase across all styles.

How do I capitalize a hyphenated word in a title?

Most styles capitalize the first element of a hyphenated compound. For subsequent elements, capitalize them if they are major words (nouns, verbs, adjectives). Keep small function words lowercase, such as "State-of-the-Art" where "of" and "the" stay lowercase.

Next Steps

Try the converter with your own text, or explore style-specific guides in the blog.

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