The Complete Guide to Title Case Conversion

Title case is one of the most common capitalization styles in the English language. You see it on book covers, newspaper headlines, email subject lines, blog post titles, academic papers, and presentation slides. The basic idea seems simple — capitalize the first letter of every important word — but the moment you try to apply it consistently, you run into a wall of contradictions. Is "with" capitalized or not? What about "is"? Does the rule change depending on where you're publishing?

The answer is yes, it changes. The three major style guides — AP (Associated Press), APA (American Psychological Association), and the Chicago Manual of Style — each have their own rules for title case. This guide walks through each one in detail, compares them side by side, covers the edge cases that trip people up, and shows you how to get it right every time.

What Title Case Actually Is

Title case is a capitalization convention where most words in a title or heading begin with an uppercase letter. It stands in contrast to sentence case, where only the first word and proper nouns are capitalized (like a regular sentence), and all caps, where every letter is uppercase. If you need to convert between these styles quickly, a sentence case converter can handle that in one click.

Every style guide agrees on the broad strokes: capitalize nouns, verbs, adjectives, adverbs, and pronouns. Always capitalize the first and last word of the title. Where they disagree is in the handling of "minor" words — articles (a, an, the), prepositions (in, of, to, for, at, by, on, up), and conjunctions (and, but, or, nor, yet, so). The disagreements are small but meaningful, especially if you're writing for a publication or academic journal that enforces a specific style.

AP Style Title Case

The Associated Press Stylebook is the default standard for journalism, marketing copy, press releases, and most web content. If you're writing a blog post, a landing page headline, or a newsletter subject line, AP style is almost certainly what your editor expects.

AP's rule can be summarized as: capitalize every word of four or more letters, plus any shorter word that functions as a noun, pronoun, verb, adjective, or adverb. Lowercase articles, prepositions, and conjunctions that are three letters or fewer — unless they're the first or last word of the title.

This means "is" (a verb) is always capitalized in AP style, even though it's only two letters. Same with "it" (pronoun), "be" (verb), "am" (verb), "or" (wait — that's a conjunction, so it stays lowercase), and "at" (preposition, lowercase). The four-letter threshold catches words like "With," "From," "Into," and "That," which are all capitalized regardless of their part of speech.

AP examples:

"A Guide to Writing for the Web" — "to," "for," and "the" are lowercase. "Guide," "Writing," and "Web" are capitalized as major words.

"She Is the One Who Walks Away" — "Is" is capitalized (verb), "the" is lowercase (article), "Who" is capitalized (pronoun, four letters), "Away" is capitalized (adverb/last word).

"What to Do in an Emergency" — "to" is lowercase (preposition, two letters), "Do" is capitalized (verb), "in" is lowercase (preposition, two letters), "an" is lowercase (article).

APA Style Title Case (7th Edition)

APA style is the standard for academic papers in psychology, education, social sciences, nursing, and business. If you're writing a research paper, thesis, or journal submission in any of these fields, APA 7th edition governs your title capitalization.

APA's definition of "major words" is explicit: nouns, verbs (including linking verbs like "is" and "are"), adjectives, adverbs, pronouns, and subordinating conjunctions ("because," "although," "since," "while," "if"). These are always capitalized. "Minor words" are articles (a, an, the), short prepositions of three letters or fewer (at, by, for, in, of, on, to, up, via), and coordinating conjunctions (and, but, for, nor, or, so, yet).

A key difference from AP: APA explicitly capitalizes all words of four letters or more. This means "With," "From," "Between," and "Through" are always capitalized. APA also has a specific rule for hyphenated compounds in titles — capitalize both parts if they're both major words (e.g., "Self-Report" not "Self-report"), but if the second element is a minor word, leave it lowercase (e.g., "Opt-in" not "Opt-In").

APA also requires capitalizing the first word after a colon, em dash, or end punctuation in a heading. So a title like "Cognitive Therapy: A New Approach" capitalizes both "Cognitive" and "A" — the latter because it follows a colon, even though "a" is normally an article that would be lowercase.

APA examples:

"Effects of Sleep Deprivation on Short-Term Memory" — "of" and "on" are lowercase (short prepositions). "Short-Term" capitalizes both parts (both are major words four letters or more).

"Why Students Drop Out: A Longitudinal Study" — "A" is capitalized because it follows the colon.

Chicago Manual of Style Title Case (18th Edition)

The Chicago Manual of Style (CMOS) is the standard for book publishing, long-form journalism, and many humanities disciplines. The 18th edition, released in 2024, brought a notable change: it now formally uses the term "title case" instead of its previous term "headline style." It also changed its rule on prepositions.

In prior editions, Chicago lowercased all prepositions regardless of length — so "between," "through," and "against" were all lowercase. The 18th edition reversed this: prepositions of five or more letters are now capitalized. "Between," "Through," "Against," "During," and "Without" all get capitalized. Short prepositions ("in," "of," "to," "for," "at," "by," "on," "up," "via") remain lowercase.

Like APA, Chicago capitalizes subordinating conjunctions ("because," "although," "while," "if," "since") and all major words. It lowercases coordinating conjunctions (and, but, or, nor, for, yet, so) and articles (a, an, the). It capitalizes the first and last word of the title and subtitle.

Chicago also has detailed rules for hyphenated compounds. The general principle: capitalize each element of a hyphenated word in a title unless it's an article, preposition, or coordinating conjunction that would otherwise be lowercase. So you'd write "Well-Known Author" but "Editor-in-Chief" (the "in" stays lowercase because it's a preposition).

Chicago examples:

"The Decline and Fall of the Roman Empire" — "and" and "of" and "the" (second occurrence) are lowercase.

"Traveling Through Eastern Europe on a Budget" — "Through" is capitalized (preposition, seven letters, per the 18th edition rule), "on" stays lowercase, "a" stays lowercase.

Side-by-Side Comparison

The differences between the three guides can be subtle. Here's where they diverge most often:

Short verbs ("is," "be," "am," "do," "go"): All three guides capitalize these. They are verbs, which are always major words. This is the rule that trips people up most — "is" looks like it should be lowercase because it's so short, but it's always capitalized in title case.

Long prepositions ("between," "through," "without"): AP capitalizes these (four or more letters). APA capitalizes these (four or more letters). Chicago 18th edition capitalizes these if five or more letters — so "from" (four letters) is capitalized in AP and APA but lowercase in Chicago. This is a new distinction since the 18th edition.

The word "to" as an infinitive marker ("How to Write"): All three guides lowercase "to" here. It's functioning as a preposition/particle, and it's only two letters. However, if "to" is the last word of the title — "A Person to Look Up To" — all three capitalize it.

Subordinating conjunctions ("because," "although," "if"): APA and Chicago capitalize these. AP capitalizes them if they're four or more letters (so "because" and "although" yes, but "if" no).

Common Mistakes and Edge Cases

"It" is always capitalized. "It" is a pronoun, and pronouns are always major words. Writing "Getting it Right" is incorrect in every style guide — it should be "Getting It Right."

"Its" vs. "It's": Both are capitalized. "Its" is a possessive pronoun, "It's" is a contraction of "it is." Both contain major-word parts.

Words after colons: APA and Chicago capitalize the first word after a colon in a title. AP style varies — if what follows the colon is a complete sentence, capitalize it; if it's a fragment, opinions differ. When in doubt, capitalize.

Phrasal verbs: In titles like "How to Give Up Sugar" or "Ways to Break Down Barriers," the particles "up" and "down" are part of phrasal verbs. AP, APA, and Chicago all treat these as adverbs, so they're capitalized. You'd write "Give Up," not "Give up."

Hyphenated words: The safest general rule is to capitalize both elements unless the second element is an article, short preposition, or short conjunction. "High-Quality" and "Long-Term" are both capitalized. "Editor-in-Chief" capitalizes "Editor" and "Chief" but not "in."

Species names, technical terms, and brand names: These follow their own rules regardless of title case. "iPhone" stays lowercase-i even in a title. Scientific species names like "Homo sapiens" follow binomial nomenclature (genus capitalized, species lowercase, both italicized).

When to Use Title Case vs. Sentence Case

Title case is the conventional choice for book titles, article headlines, major headings (H1, H2), email subject lines, and presentation titles. Sentence case is increasingly common in digital interfaces — Google's Material Design guidelines, Apple's Human Interface Guidelines, and most modern web applications use sentence case for buttons, labels, and secondary headings.

For SEO purposes, title case and sentence case perform equally well in search rankings. Google doesn't favor one capitalization style over another. The choice is about brand consistency and readability. If you're writing for the web, pick one style and stick with it across your entire site. Use a title case converter to ensure consistency without manually checking each word against style guide rules.

If you're working with body text that needs to be in proper sentence case — for example, converting an ALL CAPS paragraph from a legacy database — a sentence case converter handles that instantly. For simpler needs where you just want the first letter of every word capitalized (without style guide nuance), the capitalize words tool does exactly that.

Title Case in Programming and Technical Writing

Developers encounter a related but distinct concept: casing conventions for code. In programming, "title case" usually means PascalCase — where each word is capitalized and concatenated without spaces (e.g., UserAccountSettings). This is different from the typographic title case discussed above.

Other programming casing conventions include camelCase (userAccountSettings), snake_case (user_account_settings), and kebab-case (user-account-settings). If you're converting between these for code, those are separate tools — the point here is that "title case" in a writing context and "TitleCase" in a programming context are related concepts but follow entirely different rules.

Technical documentation often uses sentence case for headings per the Microsoft Writing Style Guide and the Google Developer Documentation Style Guide. If you're writing API documentation, README files, or developer tutorials, sentence case is generally the expected style.

Quick Reference Rules

Always capitalize: the first word, the last word, nouns, verbs (including "is," "am," "be," "are," "was," "were," "do," "does," "has," "have"), adjectives, adverbs, pronouns ("it," "its," "he," "she," "they," "my," "your").

Always lowercase (unless first/last word): "a," "an," "the," "and," "but," "or," "nor," "at," "by," "in," "of," "on," "to," "up."

Check your style guide for: prepositions of four to five letters ("from," "with," "into," "over," "upon"), subordinating conjunctions ("if," "as," "once"), and hyphenated compounds.

If you don't want to memorize any of this, paste your text into a title case converter and let the algorithm handle it. For related reading, see our guide on how Unicode text styling works if you want to go beyond capitalization and into styled text that works across platforms.

References

APA Style — Title Case Capitalization — Official APA 7th edition rules.

Chicago Manual of Style, 18th Edition — What's New — Includes the updated preposition capitalization rule.

The Writer — AP Style Capitalization Rules — AP style quick reference.