Op-Ed Insight

Case converter

Change capitalization in one click: sentence case, AP and Chicago title case, upper, lower, and the programmer cases.

This tool runs entirely in your browser and needs JavaScript switched on. Nothing you type is sent anywhere.

The conversions

Button Example
Sentence case The quick guide to writing with NASA data
Title Case (AP) The Quick Guide to Writing With NASA Data
Title Case (Chicago) The Quick Guide to Writing with NASA Data
UPPERCASE THE QUICK GUIDE TO WRITING WITH NASA DATA
lowercase the quick guide to writing with nasa data
Capitalize Each Word The Quick Guide To Writing With NASA Data
camelCase theQuickGuideToWritingWithNasaData
PascalCase TheQuickGuideToWritingWithNasaData
snake_case the_quick_guide_to_writing_with_nasa_data
kebab-case the-quick-guide-to-writing-with-nasa-data
CONSTANT_CASE THE_QUICK_GUIDE_TO_WRITING_WITH_NASA_DATA
dot.case the.quick.guide.to.writing.with.nasa.data

Each line is converted separately, so you can convert a list of headings at once. Undo restores the text from before your last conversion.

How title case works here

Both title-case buttons capitalize the first and last word, the first word after a colon or dash, and every major word: nouns, verbs, adjectives, adverbs and pronouns. They lowercase articles (a, an, the), short conjunctions (and, but, or, nor) and short prepositions (at, by, in, of, on, to, up) in the middle of a title.

The two styles differ on longer prepositions:

  • AP style capitalizes any word of four letters or more, so With, From, Into and Over are capitalized.
  • Chicago style (18th edition, 2024) lowercases prepositions of four letters or fewer, such as with, from and into, and capitalizes longer ones such as About and Between. Before 2024 Chicago lowercased prepositions of any length, so older Chicago-styled titles look different.

No converter can read meaning. “Turn off the lights” uses off as part of the verb, and most styles capitalize it: “Turn Off the Lights”. Check phrasal verbs, and words like up or over that can be either a preposition or an adverb. The guide Title case vs sentence case covers the rules in more detail.

Acronyms and brand names

Sentence case and title case keep words that are already in capitals (NASA, UK) or mixed case (iPhone, eBay). If your whole text is in capitals, every word looks like an acronym, so the converter lowercases everything first; fix acronyms by hand afterwards. Sentence case also capitalizes the pronoun I.

The programmer cases split words at spaces, punctuation and existing capital letters, so “userID” becomes “user_id” in snake_case. Accented letters are kept.

Which case should headings use?

Many style guides for the web, including several government ones, prefer sentence case for headings because it is easier to read and to apply consistently. Books, newspapers and academic titles often use title case. Pick one and use it everywhere.