Case Converter
Twelve cases, with title case that follows a style guide rather than capitalising everything.
- Title CaseHeadlines and titles, following a style guide rather than capitalising everything.
- Sentence caseFirst letter of each sentence, everything else down.
- UPPER CASEEverything capitalised.
- lower caseEverything down.
- camelCaseJavaScript variables and JSON keys.
- PascalCaseClass and component names.
- snake_casePython, Ruby, and most SQL columns.
- kebab-caseURLs, CSS classes and file names.
- CONSTANT_CASEEnvironment variables and constants.
- dot.caseConfig keys and namespaces.
- aLtErNaTiNgThe sarcasm one.
- iNVERTSwaps the case of every letter, for when caps lock was on.
Title case here follows a style guide rather than capitalising every word, which is the thing most converters get wrong. Acronyms already in capitals are left alone, so NASA does not become Nasa, and hyphenated compounds are cased on both halves, giving “Self-Portrait” rather than “Self-portrait”.
The programmer cases understand existing camelCase and PascalCase, so converting XMLHttpRequest to snake_case gives xml_http_request rather than one long run.
How the Case Converter works
Paste text once and get all twelve conversions at once: title, sentence, upper, lower, camel, Pascal, snake, kebab, constant, dot, alternating and inverted. The title case follows Chicago or AP rather than capitalising every word, which is the thing nearly every other converter gets wrong.
Also known as: title case converter · uppercase to lowercase · camel case converter · snake case converter · capitalize text online
Title case is not capitalising every word
Paste a headline into almost any online case converter, ask for title case, and you get every word capitalised: "The Lord Of The Rings". That is Start Case. It is not what any style guide means by title case, and it is the single most common thing these tools get wrong.
Actual title case capitalises the first and last words always, and capitalises everything in between except articles, coordinating conjunctions and prepositions. So "The Lord of the Rings", "A Tale of Two Cities", "What to Look for in a Partner". The rule about the last word matters more than it looks: "This Is the End of It" keeps its final "It" capitalised even though "it" would otherwise be lower.
Getting this right is the difference between a headline that reads as edited and one that reads as processed. It is also the reason this tool asks which style you want rather than pretending there is one answer.
Chicago and AP disagree, and both are right
The two dominant English style guides draw the line in different places. The Chicago Manual of Style, rule 8.159 in the seventeenth edition, lower-cases prepositions regardless of how long they are. So Chicago gives "Notes toward a Supreme Fiction" and "A Room with a View".
The Associated Press Stylebook capitalises any word of four letters or more, including prepositions. So AP gives "Notes Toward a Supreme Fiction" and "A Room With a View". Books, academic writing and long-form editorial tend to follow Chicago; news and a great deal of web copy follow AP.
Neither is a mistake and there is no third option that splits the difference. What does look like a mistake is mixing them inside one publication, which is what happens when different people paste headlines into different converters. Pick one and use it.
There is a further wrinkle worth knowing: a published title is set by its publisher's house style and may match neither guide. Stevens's poem is printed with a capital T on "Toward" whatever Chicago says, because that is how the publisher set it. A converter can apply a rule; it cannot know what a particular publisher decided.
Acronyms, hyphens and the cases that break converters
Two more places these tools fail. The first is acronyms: a converter that lower-cases everything before capitalising the first letter turns NASA into Nasa and PDF into Pdf. Here, a word already in full capitals is left exactly as it is, on the reasoning that nobody typing NASA wanted it changed.
The second is hyphenated compounds. "Self-portrait" in a title should be "Self-Portrait", with both halves capitalised, and a converter that treats the hyphen as part of the word gives "Self-portrait". Each side of a hyphen is cased separately here, with the lower-case rules still applying to the parts, so "Ten-of-Swords" comes out with its preposition down.
The programmer cases and the boundaries inside them
camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE and dot.case are all the same operation with a different joiner: find the word boundaries, normalise the words, put them back together. Everything interesting is in finding the boundaries.
Spaces, hyphens, underscores and dots are obvious breaks. The one that catches naive implementations is a boundary inside an existing camelCase or PascalCase string, where there is no separator at all. Convert XMLHttpRequest to snake case without looking for those and you get xmlhttprequest; look for them and you get xml_http_request, which is what you meant.
There are two boundaries to detect. A lowercase letter or digit followed by an uppercase letter is one, which handles the ordinary camel hump. A run of uppercase letters followed by an uppercase letter and then a lowercase one is the other, which is what separates XML from Http in XMLHttpRequest rather than splitting the acronym into individual letters. Both are applied here before anything else happens.
Frequently asked questions
What is wrong with capitalising every word?
That is Start Case, not title case. Real title case leaves articles, coordinating conjunctions and prepositions in lower case unless they open or close the title, so "The Lord of the Rings" rather than "The Lord Of The Rings". It is a small difference that makes a headline look edited rather than generated.
Which title case style should I pick?
Chicago if you are writing a book, an academic paper or long-form editorial; it lower-cases prepositions regardless of length. AP if you are writing news or most web copy; it capitalises anything of four letters or more. Neither is more correct, but mixing them within one publication looks careless.
What happens to acronyms?
A word already in full capitals is left as it is, so NASA stays NASA rather than becoming Nasa. That is the behaviour you want almost every time, and it is why pasting a title that already contains an acronym does not damage it.
Does it understand existing camelCase?
Yes. The word boundaries inside camelCase and PascalCase are detected before conversion, so XMLHttpRequest becomes xml_http_request in snake case rather than one undivided run. Mixed separators are handled too: hyphens, underscores, dots and spaces are all treated as breaks.
Is my text sent anywhere?
No. It all happens in the page, and nothing is uploaded or stored.
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