When Should I Use Title Case?

Capitalisation style feels trivial until a site has two hundred pages and three conventions running at once. The rules themselves are simple; the disagreements between style guides are where the time goes.

The two main styles

Title Case capitalises the first word, the last word, and every major word in between. Articles, short prepositions and coordinating conjunctions stay lowercase.

The Sound of the Sea and the Wind in the Trees

Sentence case capitalises the first word and any proper nouns, exactly as a sentence would.

The sound of the sea and the wind in the trees

There is also Start Case, which capitalises every word without exception, and it is usually a sign that a converter was run without anyone reading the result afterwards.

What stays lowercase in title case

Broadly:

• Articles: a, an, the
• Coordinating conjunctions: and, but, or, nor, for, yet, so
• Short prepositions: of, in, on, at, to, by, up, as

Everything else is capitalised: nouns, pronouns, verbs including is and are, adjectives, adverbs, and subordinating conjunctions such as because and although.

Two overrides apply regardless of the above: the first and last words are always capitalised, and a word following a colon usually is.

Where the guides disagree

This is the genuine source of confusion, because there is no single correct answer to appeal to.

Preposition length. The Chicago Manual of Style lowercases prepositions regardless of length. AP style capitalises prepositions of four letters or more, so With, From and Over take capitals. APA capitalises words of four letters or more generally.

Verbs. Every guide capitalises Is and Are, and writers lowercase them constantly by instinct because they look small and unimportant. They are neither.

Hyphenated compounds. Chicago capitalises both parts of most hyphenated terms, giving Well-Known. Others capitalise only the first, giving Well-known. Both appear in respectable publications and neither is wrong.

If you need a defensible rule without arbitrating between guides: capitalise everything except articles, coordinating conjunctions and prepositions of three letters or fewer, always capitalising the first and last words. That sits close enough to every major guide to pass without comment.

Where each style belongs

Title case suits book and film titles, newspaper headlines in the American tradition, formal document titles, and anywhere a heading should read as a name rather than a statement.

Sentence case suits interface text, buttons, menus, form labels, most British publications, technical documentation, email subject lines and modern web headings.

The shift towards sentence case in digital writing is well established and for good reasons. It reads marginally faster, it sidesteps the preposition arguments entirely, and it handles long headings far better, since a ten-word heading in title case starts to look like shouting.

Styles worth avoiding

ALL CAPS for anything longer than a short label. It is measurably slower to read, because the distinctive shapes of words disappear when every letter is the same height. It is also widely read as shouting, and screen readers handle it inconsistently, sometimes spelling out words letter by letter.

Random Capitals For Emphasis in running text. Emphasis is what italics are for, and capitals used this way read as either archaic or overexcited.

The rule that matters more than which style

Consistency. A site where half the headings are title case and half are sentence case looks unconsidered, and readers register the inconsistency long before they could tell you which convention was used where.

Pick one for headings, one for buttons and labels, write it down somewhere findable, and apply it. If the two differ, which is both common and sensible, write down which is which so the next person does not have to guess.

Converting existing text

Automated conversion handles the bulk correctly and gets the edge cases wrong in predictable ways. Watch for:

• Acronyms, which must stay uppercase. A naive converter turns NASA into Nasa and API into Api.
• Proper nouns, which stay capitalised even in sentence case. Converting a title to sentence case should not lowercase London or Tuesday.
• Brand names with deliberate casing, such as iPhone or eBay, which most converters mangle on sight.
• Roman numerals, where Part IV becomes Part Iv.

Convert automatically, then read the result. The exceptions are few enough to fix by eye and numerous enough that skipping the check always shows.

The one case that is not a style choice

URL slugs are not a capitalisation decision. They should be lowercase, always, because some web servers treat uppercase and lowercase paths as different addresses while others do not.

A link written with a capital letter can therefore lead to a page that exists on one server and returns an error on another, and the same page reachable at two addresses splits its search signals between them. Lowercase removes the whole class of problem.

Titles that work regardless of case

One thing worth remembering while arguing about capitals: the case of a heading matters far less than whether it says something.

A heading that front-loads the actual subject will outperform a beautifully capitalised one that buries it. Get the words right first, then decide how to capitalise them, because no amount of correct casing rescues a heading nobody understands.