Case Converter
Every case at once, including the four title-case rules that disagree with each other.
Automatic keeps NASA, but lowercases a SHOUTED LINE.
Where the style guides disagree
| Word | AP | Chicago | APA | MLA |
|---|
Writing
- Sentence case
One capital per sentence. Abbreviations and initials do not start a new one.
- Title Case — AP
Prepositions of four letters or more get a capital. Newsrooms and most blogs.
- Title Case — Chicago
Every preposition stays lowercase. Books, and most published non-fiction.
- Title Case — APA
Like AP, but both halves of a hyphenated compound get a capital.
- Title Case — MLA
Like Chicago, but a bound prefix does not lowercase what follows it.
- Capitalise Each Word
Every word, minor ones included. Common, and not title case in any guide.
- UPPER CASE
Every letter capitalised.
- lower case
Every letter lowercased, acronyms included.
Code
- camelCase
JavaScript variables, Java methods.
- PascalCase
Type and component names.
- snake_case
Python, Ruby, SQL columns.
- kebab-case
URLs, CSS classes, file names.
- CONSTANT_CASE
Environment variables and constants.
- Train-Case
HTTP headers: Content-Type, X-Request-Id.
- dot.case
Config keys and namespaced properties.
Other
- aLtErNaTiNg
Alternates on letters only, so spacing does not break the rhythm.
- iNVERSE
Swaps every letter. Rescues a line typed with caps lock on.
Everything here runs on your device. Nothing you enter is uploaded or stored.
Paste text once and get all seventeen cases at the same time — sentence case, title case in four different style guides, UPPER, lower, camelCase, snake_case, kebab-case and the rest — with a copy button on each and no mode to choose first.
How to use it
- Paste or type into the box. Every result updates as you type.
- Read the case you need and press Copy on that row.
- Press Replace instead to write a result back into the box, which lets you chain conversions — sentence case, a manual fix, then kebab-case.
- If your text contains acronyms and the automatic handling reads them wrong, switch the acronym control to Keep or Lowercase.
- Check the disagreement table under the results to see which words the four title-case guides set differently.
Title case is a style decision, not a transformation
Most converters offer one “Title Case” button, which quietly means “capitalise every word except a handful of small ones”. That is not what any published style guide says, and the guides do not agree with each other either.
The largest split is prepositions. AP and APA capitalise any preposition of four letters or more, giving A River Runs Through It. Chicago and MLA lowercase every preposition regardless of length, giving A River Runs through It. Both are correct; they are correct for different publications.
Hyphens split the guides a second way. APA capitalises both halves of every compound, so The Log-In Screen. AP, Chicago and MLA lowercase the second half when it is itself a minor word, so The Log-in Screen. Chicago adds a further rule: when the first element is a prefix that cannot stand alone — anti-, re-, non-, post- — the second element stays lowercase, giving The Anti-intellectual Turn where MLA writes The Anti-Intellectual Turn.
All four guides do agree on three things, and they are the three a naive converter usually breaks: the first word is always capitalised, the last word is always capitalised even when it is “the” or “for”, and the first word after a colon starts fresh. What Are You Waiting For has a capital F for that reason.
Rather than pick a guide for you, this runs all four and lists the words where the answer differs. When the table is empty, every guide agrees and the result is simply right.
What it does not do
It does not know proper nouns. Sentence case lowercases “paris” because no dictionary ships with a browser tool — capitalise names yourself after converting. It cannot resolve a genuinely ambiguous full stop: in “I live in the U.S. Tomorrow I leave”, the dot both ends an acronym and ends a sentence, and no rule settles that without understanding the meaning. The abbreviation list is curated rather than complete, and deliberately excludes short forms that are also ordinary words, so “no.” and “min.” are read as sentence endings.
Everything runs in your browser. Nothing you paste is uploaded, logged or stored, and closing the tab discards it — there is no draft saved anywhere.
What each style guide does
| Rule | AP | Chicago | APA | MLA |
|---|---|---|---|---|
| Prepositions under 4 letters | lower | lower | lower | lower |
| Prepositions of 4+ letters | Upper | lower | Upper | lower |
| Articles: a, an, the | lower | lower | lower | lower |
| Coordinators: and, but, or, for | lower | lower | lower | lower |
| Second half of a hyphenated compound | minor words lower | minor words lower | Upper | minor words lower |
| After a prefix that cannot stand alone | Upper | lower | Upper | Upper |
| First and last word | Upper | Upper | Upper | Upper |
| First word after a colon | Upper | Upper | Upper | Upper |
The code cases
| Case | Output | Used for |
|---|---|---|
| camelCase | helloWorldAgain | JavaScript variables, Java methods |
| PascalCase | HelloWorldAgain | Types, classes, components |
| snake_case | hello_world_again | Python, Ruby, SQL columns |
| kebab-case | hello-world-again | URLs, CSS classes, file names |
| CONSTANT_CASE | HELLO_WORLD_AGAIN | Environment variables |
| Train-Case | Hello-World-Again | HTTP headers |
| dot.case | hello.world.again | Config keys |
Questions
Which title case is the correct one?
There is no single correct one. AP and APA capitalise prepositions of four letters or more, so "Runs Through It". Chicago and MLA lowercase every preposition however long, so "Runs through It". Pick the guide your publication, journal or style sheet follows. If nobody has told you, AP is the safe default for web and blog headlines.
Why does sentence case leave "Mr. Smith" alone?
Because splitting on every full stop is wrong. A dot followed immediately by more letters is inside an abbreviation or acronym, and a dot after a known short form like Mr., etc. or e.g. does not end a sentence either. Both rules are applied before a capital is placed, which is why pasted prose survives intact.
What happens to acronyms like NASA or iPhone?
They are left as typed. A word in all capitals, or one with a capital after the first letter, is read as deliberate. The exception is text that is mostly capitals, which is treated as shouted and lowercased — otherwise an all-caps headline would come back unchanged. Set the acronym control to override either behaviour.
Does it change my spacing or punctuation?
The writing cases do not. Line breaks, runs of spaces, dashes and quotes come back exactly as you typed them, because only letters are touched. The code cases are different by necessity — camelCase, snake_case and the rest discard punctuation, since an identifier cannot contain it.
Is my text uploaded anywhere?
No. Every conversion runs in your browser as you type. Nothing is sent to a server, logged or stored, which matters when the text is an unpublished headline or a client's copy.
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