AP Style Capitalization Tool
Convert any headline or title to AP Stylebook capitalization. Capitalizes principal words, lowercases articles and short prepositions (under 4 letters), and follows the AP rules for headlines, photo captions, and newsroom copy.
How to capitalize a headline in AP style
1. Paste the headline or title
Drop a headline, photo caption, subhead, or section title into the left textarea. The AP-style version appears in the lower textarea immediately. The sidebar shows the same text rendered in Chicago, APA, all-caps, and sentence case so you can pick the right style for the surface you are publishing on.
2. Read the AP-style rules the tool applies
AP Stylebook prescribes:
- Capitalize the principal words: nouns, verbs, adjectives, adverbs, pronouns, subordinating conjunctions.
- Lowercase articles (a, an, the), conjunctions of 3 letters or fewer (and, but, or, nor, for), and prepositions of 3 letters or fewer (of, on, in, at, by, to, up, as, if).
- Always capitalize the first and last word, regardless of length.
- Capitalize prepositions of 4+ letters (with, from, into, over, after, before).
3. Copy the output
The Copy AP button puts the AP-style version on the clipboard. The original input is preserved in the source textarea. You can iterate by editing the source and watching the output reflow.
4. Compare against other styles
The right-side card shows the same headline in five styles. AP and Chicago look similar but Chicago capitalizes all prepositions of 4+ letters where AP follows the same rule but applies it less strictly to compound words. APA is stricter: every word of 4+ letters is capitalized regardless of part of speech.
The AP Stylebook capitalization rule explained
The Associated Press Stylebook is the dominant style guide for American news. Its capitalization rule for headlines is one of the cleanest in the industry, which is why it spread to PR, marketing copy, and most corporate blog posts.
The 4-letter rule
Words of 4 or more letters are capitalized. Words of 3 or fewer letters are lowercased UNLESS they are the first or last word of the headline, or unless they are a noun, verb, or other principal word that is part of the meaning. So "How To Read" capitalizes "To" because it is the last word, but "How to Read the News" lowercases "to" because it sits mid-sentence and is a 2-letter preposition.
Why 4 letters and not 5?
AP picked the 4-letter rule because the four most common headline-killing prepositions in English (with, from, into, over) are all 4 letters and need to be capitalized to read cleanly. The rule landed on 4 letters to draw the line just below them.
Capitalize verbs always
Short verbs (is, be, are, was, has) are exceptions to the under-4-letters lowercase rule because they are still principal words. "How Tax Cuts Are Made" capitalizes "Are" even though it is 3 letters. The tool detects "is/are/was/be" and capitalizes them.
AP vs Chicago vs APA vs MLA
| Style | Lowercase under N letters | Verbs | Prepositions |
|---|---|---|---|
| AP Stylebook | 3 (a, an, the, and, but, or) | Always cap (is, are, be) | 4+ letters caps; 3- lowercase |
| Chicago / Title Case | 3 (similar list) | Always cap | All prepositions lowercase, regardless of length |
| APA | 3 | Always cap | 4+ letters caps; 3- lowercase |
| MLA | 3 | Always cap | 4+ letters caps; 3- lowercase |
The big divergence is Chicago. Chicago lowercases every preposition regardless of length, which is why Chicago headlines often look like "The Bridge over the River Kwai" (over stays lower) while AP would write "The Bridge Over the River Kwai" (over caps because 4 letters).
For most newsrooms and PR, AP is the default. For most academic publications, Chicago. For psychology and education research, APA. The differences are small but the consistency matters within a publication.
AP capitalization edge cases
Hyphenated compounds
Both parts are capitalized in AP if both are principal words: "Stay-at-Home Mom", "Open-Source Software", "Self-Driving Car". The tool capitalizes the segment before and after the hyphen separately.
Acronyms and initialisms
All caps for initialisms (NYT, FBI, AP). Title case for acronyms pronounced as words (Nasa is the AP house style, NASA is Chicago/APA). The tool preserves all-caps strings as-is.
Brand names
Some brand names mix case (iPhone, eBay, IKEA). The tool does not maintain a brand dictionary; it lowercases or uppercases the first letter only. If brand names appear in your headline, override the tool output manually.
Subtitles after colon
AP treats text after a colon as a new title. The word right after the colon is capitalized even if it would otherwise be a 2-letter preposition. The tool does not currently parse colons specially; capitalize manually if a colon appears mid-headline.
Privacy and processing
All conversion runs in your browser. Headlines, photo captions, and unpublished drafts stay local. The tool does not log keystrokes, does not call any API, and does not store the source text. Safe for embargoed news copy, internal drafts, and headlines under NDA.
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Frequently asked questions
What is AP style capitalization?
AP Stylebook capitalization is the style most newsrooms and PR teams use. Capitalize principal words (nouns, verbs, adjectives, adverbs, pronouns). Lowercase articles (a, an, the), short conjunctions (and, but, or, nor), and prepositions of 3 letters or fewer (of, on, in, at, by, to). Always capitalize the first and last word.
Does AP capitalize prepositions?
Yes if they are 4 letters or longer (with, from, into, over, after, before). No if they are 3 letters or fewer (of, on, in, at, by, to, up). This is the AP 4-letter rule.
Is is capitalized in AP style headlines?
Yes. Verbs are always capitalized in AP, even short ones (is, are, be, was, has). The rule about lowercasing under-4-letter words applies to articles, conjunctions, and prepositions only - not verbs.
How is AP different from Chicago title case?
AP capitalizes prepositions of 4 or more letters (Over, From, With). Chicago lowercases all prepositions regardless of length. So 'Over the River' becomes 'Over the River' in AP but 'over the River' in Chicago. The first-word and last-word rule applies in both.
Do I capitalize a after a colon in AP?
Yes. AP treats text after a colon as a fresh title, so the first word after the colon is capitalized even if it would otherwise be lowercased. The tool does not currently auto-detect colons; override manually if the headline contains one.
How are hyphenated words handled?
Both halves are capitalized if both are principal words (Stay-at-Home Mom, Open-Source Software). The tool capitalizes the segment before and after each hyphen separately.
What about brand names like iPhone or eBay?
Brand names with intentional non-standard casing should be preserved as-is. The tool does not maintain a brand dictionary, so it will write 'Iphone' and 'Ebay'. Override these manually after copying the output.
Is the text sent to a server?
No. All conversion runs in your browser via JavaScript. Embargoed news copy, headline drafts, and internal PR copy stay on your device. The tool makes no network call when you paste or copy. See also: Chicago Title Capitalization. See also: APA Capitalization Tool. See also: MLA Capitalization Tool. See also: Email Title Capitalization.
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