Using the title case converter
Paste a title and pick the guide from Style guide. The result updates as you switch, so you can see where AP and Chicago part ways on your own headline.
Put one title on each line to convert a batch. A word you've capitalised on purpose, like NASA or iPhone, is left as it is. If the whole title arrived in capitals, those capitals carry no information and everything is reset first.
One title, four guides
Take "a walk through the woods with nothing but a map". AP writes A Walk Through the Woods With Nothing but a Map, because it only lowercases prepositions of three letters or fewer. APA agrees with AP here.
Chicago writes Through with a capital and with in lowercase. MLA lowercases both, because it keeps every preposition small however long it is: A Walk through the Woods with Nothing but a Map.
They all agree on the first word, on the articles, and on the word after a colon. AP, Chicago and MLA also capitalise the last word, even a small one, so "What Is It Good For?" ends with a capital. APA's guidance doesn't mention the last word, and this tool leaves it to the usual rule.
The 2024 change to Chicago
For decades Chicago lowercased prepositions of any length. The 17th edition would write "Much Ado about Nothing", and plenty of style sheets still say so.
The 18th edition, published in 2024, changed it. Prepositions of five letters or more now take a capital, and the manual's own example sets the old and new side by side. It's A Room with a View, but Much Ado About Nothing.
This tool follows the 18th edition. If your publisher is still on the 17th, the MLA setting gives the older Chicago result for most titles, since both lowercase long prepositions.
What a word list can't tell
Two rules depend on grammar, not spelling. AP capitalises "to" when it's part of a verb, as in its example What I Want To Be When I Grow Up, where Chicago keeps Born to Run lowercase. And AP capitalises both parts of a phrasal verb, so it writes Turn Off the Lights.
Telling those apart means parsing the sentence, and a converter that guesses will be wrong in both directions. This one leaves "to" and phrasal-verb particles lowercase, and you'll want to fix those two cases by hand.
Related conversions
Sentence case is the other way to set a headline, with a capital on the first word and on names only. It's the simpler rule to follow consistently.
Questions
Which title case style should I use?
The one your publisher, school or newsroom uses. Journalism is mostly AP, books mostly Chicago, psychology and the social sciences APA, and humanities papers MLA. If nobody has told you, pick one and use it consistently.
Is "with" capitalised in a title?
In AP and APA, yes, because it has four letters. In Chicago and MLA it stays lowercase, since Chicago lowercases prepositions up to four letters and MLA lowercases all of them.
Do you capitalise the word after a colon?
Yes, in all four guides. A subtitle after a colon starts as if it were a new title.
What happens to hyphenated words?
Each part is treated as a word of its own, so Self-Report and Anti-Intellectuals take two capitals. A small word inside a compound, like "in" in Mother-in-Law, stays lowercase.