Text case converter

About this tool

Two different jobs share one page here, because they share one hard part. Renaming userProfileImageURL to user_profile_image_url and capitalising the world according to garp correctly both start by working out where one word ends and the next begins. Once the text is split into words, every programmer case is a trivial rejoin — and title case is anything but.

The programmer cases are unambiguous — there is only one correct camelCase. Title case is not: several style guides give different answers to the same title. This page follows Chicago 18th, which is the one most general writing and publishing works to, and says so rather than leaving you to guess. If you are writing to APA, MLA or a newsroom stylebook, check the differences below before using the result.

How it works

Every line is handled on its own, so a pasted list of twenty identifiers comes back as twenty converted identifiers rather than one run-on string. Blank lines are preserved.

Splitting a line into words is the part that actually matters. Separator characters — spaces, underscores, hyphens, full stops, forward and back slashes — are treated as word boundaries. Then two more boundaries are inserted: between a lower-case letter or digit and a following capital (so userName becomes user Name), and between a run of capitals and a capital that starts a lower-case word (so XMLHttpRequest becomes XML Http Request, not X M L Http Request). That second rule is what keeps acronyms intact; without it, every initialism in your codebase would be shredded one letter at a time.

Title case then works on those words, against embedded lists of articles, coordinating conjunctions and prepositions. It lowercases articles, the coordinating conjunctions, and prepositions of four letters or fewer; everything else is capitalised, including prepositions of five letters or more. The first and last words are always capitalised, as is the first word after a colon, em dash or end punctuation. Both halves of a hyphenated word are capitalised.

Which title case this uses, and where others differ

This page follows Chicago 18th. Lowercase articles, the coordinating conjunctions, and prepositions of four letters or fewer; capitalise everything else, including prepositions of five letters or more; always capitalise the first and last word. The September 2024 edition changed this — every earlier edition lowercased all prepositions regardless of length, which is why The World according to Garp is the textbook example of old Chicago and The World According to Garp is the current one.

Other guides differ, and if you are writing to one of them the result here will need adjusting:

• APA 7thCapitalises every word of four letters or more, so with and from are capitalised where Chicago lowercases them. It also does not force-capitalise the last word, so a title ending in a preposition keeps it lowercase — What It Is Made of, where Chicago gives Made Of.
• MLALowercases prepositions regardless of length, in MLA's own words "no matter how long those words are". MLA still produces The World according to Garp and All about Eve.
• Newsroom styleCapitalises on length alone — four letters or more, prepositions included — and capitalises the last word. Close to APA, but not identical.

If you need one of those exactly, the difference is nearly always a preposition, and it is usually one word. Read the result before you use it rather than assuming any tool has your house style.

Common questions

Why Chicago and not one of the others?

Because it is the one most general writing works to, and because for a page whose main job is converting identifiers, a style-guide picker was more machinery than the job needed. If you are writing to APA, MLA or a newsroom stylebook, the section above lists exactly where they diverge — it is almost always a single preposition.

Should "according" be capitalised?

Under Chicago 18th, yes — it is nine letters, and the 2024 edition capitalises prepositions of five or more. Under MLA, no. The World according to Garp is correct MLA and looks like a typo to most people; The World According to Garp is what this page gives you.

Why is my acronym coming out as Xmlhttprequest?

Because prose cases lower-case everything they are not capitalising, and the tool has no way to know XML is an initialism rather than a word. The programmer cases keep the split correct — XMLHttpRequest becomes xml_http_request and back to XMLHttpRequest as PascalCase — but sentence case and title case will flatten it. Fix acronyms by hand afterwards; a fixed list of known initialisms would be wrong for whatever yours happens to be.

Does it handle non-English text?

Partly. Case conversion uses the browser's own Unicode-aware toUpperCase and toLowerCase, so accented characters convert correctly. But the word-splitting rules and every title-case word list are English, and both APA and MLA capitalise titles in other languages sentence-style rather than title-style anyway. Treat title case here as English-only.

Is anything I paste stored or sent?

No. There is no network request on this page after it loads, and nothing is written to storage except your light/dark theme preference. Reload and the text is gone.

Known limitations

• Participial prepositions are undecidable hereChicago lowercases according, concerning, during, considering and similar words when they act as prepositions, and capitalises them when they act as verbs. The World according to Garp and Teachers According More Time to Students need opposite treatment of the same word. Telling them apart needs a grammatical parser, not a word list — this page treats them as prepositions, which is right far more often than not, but it is a guess in the rare case where it isn't.
• Chicago 18th is implemented from secondary reportingThe 18th edition's full text sits behind a subscription, and Chicago's own free Q&A page still serves the 17th-edition answer. The five-letter preposition rule and the dropped prefix rule are consistent across several independent sources but have not been confirmed against the manual itself. This matters more now that Chicago is the only title case offered here.
• Chicago's paired-preposition option is not appliedThe 18th edition permits, but does not require, capitalising a short preposition when it is paired with a long one — For and Within alongside for and Within. Since it is optional, two careful editors can legitimately disagree. This page always takes the lowercase reading.
• The preposition list is fixed and finiteTitle case needs to know which words are prepositions, and that comes from a list embedded in the page. It covers the common English prepositions; an unusual or archaic one will be treated as an ordinary word and capitalised.
• Proper nouns are not recognisedSentence case and the lower-case output will flatten names, brands and initialisms along with everything else, because nothing here knows what a proper noun is. Check the output before using it.

The same job at the command line

• tr '[:lower:]' '[:upper:]' < file.txtUpper-cases everything. Swap the two arguments for the reverse. Byte-oriented, so it will not handle accented characters correctly.
• sed -E 's/([a-z0-9])([A-Z])/\1_\2/g' file.txt | tr '[:upper:]' '[:lower:]'camelCase to snake_case, one boundary rule only — it will split XMLHttpRequest badly, which is exactly the case this page handles separately.
• python3 -c "import sys;print(sys.stdin.read().title())"Python's naive title case. Capitalises every word including articles and prepositions, and breaks on apostrophes — don't becomes Don'T. Not any style guide's title case.
• awk '{print toupper(substr($0,1,1)) tolower(substr($0,2))}' file.txtSentence case per line, ignoring sentence boundaries within the line.