Two different jobs
Sentence case and title case solve two different problems. Both end up capitalizing words in a heading, but the rule behind each one is different. Sentence case capitalizes the first word and nothing else. It works the same way an ordinary sentence does. Title case capitalizes most of the important words, the way a book title or a headline does. Neither one is more correct in general. Each fits a different kind of writing. Mixing them inconsistently on the same page is what actually looks wrong.
Sentence case, in practice
Sentence case looks like this: “Getting started with your account.” Only “Getting” is capitalized. Proper nouns still get capitalized too, the same as in any other sentence. This is the default for most modern software. Buttons, menu items, and page headings in web apps now lean heavily toward sentence case. Google, Microsoft, and Apple all moved their major products this way in their interface guidelines. Most design systems built since then followed along.
Part of the appeal is practical. Sentence case is faster to write correctly. A writer doesn’t have to remember a rule for every single word. It also reads a little faster, since it looks like ordinary text rather than a decorated label. For UI copy, error messages, and documentation headings, sentence case is the safer default today.
Title case, in practice
Title case looks like this: “Getting Started With Your Account.” Even that short example gets capitalized differently depending on which style guide you ask, as you’ll see below. Title case still dominates print headlines and book titles. Formal reports and academic writing use it too. It signals formality in a way sentence case doesn’t. A book titled “getting started with your account” would read as a mistake, not a style choice.
The tricky part: “capitalize the important words” isn’t a precise rule by itself. Every major style guide gives a specific answer for which words count as important. Those answers don’t all agree.
Where the four style guides diverge
| Style | Prepositions | Hyphenated compounds |
|---|---|---|
| AP | lowercase under 4 letters | capitalize both parts |
| Chicago | lowercase any length | lowercase the second part if it’s a small word |
| MLA | lowercase any length | capitalize both parts |
| APA | lowercase under 4 letters | capitalize both parts |
All four agree on the easy cases. Capitalize the first and last word of a title. Capitalize the word right after a colon. Lowercase articles like “a,” “an,” and “the.” Lowercase coordinating conjunctions like “and,” “but,” and “or.” Lowercase the infinitive “to.” Where the four styles split is prepositions and hyphens.
AP and APA both lowercase short prepositions. Anything under four letters — “of,” “in,” “for,” “with” — stays lowercase. Longer ones like “over,” “under,” and “between” get capitalized. Chicago and MLA take a simpler stance: lowercase every preposition, no matter how long. That’s why “Rise over the Hill” is correct under AP rules. “Rise Over the Hill” is correct under Chicago rules. Same four words, opposite answer.
Hyphenated compounds split a different way. AP, MLA, and APA all capitalize both halves of a hyphenated word. It doesn’t matter what the word is, so “Up-To-Date” is correct in all three. Chicago is the outlier. If the second half of the pair would normally be lowercase on its own — an article, a preposition, a conjunction — Chicago lowercases it there too. That gives “Up-to-Date” instead.
Why one naive rule is not enough
Most online title case converters use a single shortcut. They capitalize every word longer than three or four letters and call it done. That gets the common cases right. It gets the rest quietly wrong, because it has no concept of which style guide it’s supposed to follow. It has no concept of the colon rule either, and no concept of the hyphen exception at all. A tool that always capitalizes “Over” is wrong for Chicago and MLA writers. A tool that always lowercases “over” is wrong for AP and APA writers. Neither one tells you which assumption it made.
The case converter on this site computes all four style guides separately, from the actual published rule for each one. It shows every output at once, so you can see exactly where they diverge — including the hyphen exception, which most tools skip entirely.
Choosing which one to use
Sentence case is the safer default for UI copy, technical documentation, and error messages. It reads as current and low-friction. Use full title case only when a specific publication requires it — a newspaper following AP, a paper following MLA or APA, a book publisher following Chicago. Follow that guide’s rules exactly rather than a generic approximation.
Whichever style you pick, the real requirement isn’t which one you choose. It’s staying consistent with it across every heading in one document. That’s the kind of thing a heading structure checker can catch once a document has grown too long to eyeball.
Check your own text
Paste a title or heading into the case converter. You’ll see it rendered in sentence case and all four title case styles side by side. Each style’s rule is cited too, so you can check it against the current edition yourself.