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Text case styles explained: UPPERCASE, Title Case, camelCase & more

Writers, developers and marketers all need to change how text is capitalised — but they're rarely talking about the same style when they say “change the case.” Here's what each one actually means, where it comes from, and when to reach for it.

Guide · 5 min read

“Can you change the case?” means something different depending on who's asking. A writer might mean switching a heading from ALL CAPS to normal sentence case. A developer might mean turning “user name” into userName for a variable. There are really two families of case style in everyday use — the writing ones, built around grammar and readability, and the programming ones, built around what characters are actually allowed in a file name or a piece of code — and knowing which one a situation calls for saves a lot of back-and-forth.

The everyday writing cases

These are the case styles you'll meet in headings, titles and ordinary prose.

  • Sentence case — only the first word and any proper nouns are capitalised, exactly like a normal sentence: Convert your PDF to Word for free. This is the style most style guides now recommend for headings and UI text, because it's faster to read and looks less like shouting than Title Case.
  • Title Case — most of the significant words are capitalised: Convert Your PDF To Word For Free. Traditional for book and film titles, and still common in US headline writing, though which small words (“a”, “the”, “of”) get capitalised varies by style guide — AP, Chicago and APA each have slightly different rules.
  • UPPERCASE — every letter capitalised: CONVERT YOUR PDF TO WORD. Useful for short emphasis, acronyms and some logos, but long stretches of it are genuinely harder to read (see the FAQ below) and reads as shouting in most written contexts.
  • lowercase — no capital letters at all, even at the start of a sentence. Rare in formal writing, but a deliberate stylistic choice for some brands, poetry and casual messaging.

The programming cases

Code usually can't contain spaces in a name, so these styles substitute capital letters, underscores or hyphens to keep multi-word names as one unbroken token — and different languages and contexts have settled on different conventions.

  • camelCase — firstName, getUserData. The standard for variable and function names in JavaScript and Java; the first word stays lowercase, every word after it gets a capital.
  • PascalCase — FirstName, UserProfileCard. Same idea as camelCase but the first word is capitalised too. The convention for class names in most languages, and for component names in frameworks like React.
  • snake_case — first_name, is_available. Words joined with underscores. Standard for variables and functions in Python and Ruby, and very common for database column names and config keys.
  • kebab-case — first-name, user-profile-card. Words joined with hyphens. The convention for URL slugs, HTML/CSS attribute names and custom HTML elements — browsers and search engines both treat hyphenated URLs as more readable than underscored ones.
  • CONSTANT_CASE (also called SCREAMING_SNAKE_CASE) — MAX_RETRIES, API_BASE_URL. Uppercase snake_case, conventionally reserved for constants and environment variables so they visually stand out from ordinary variables in the same file.

The playful ones

Alternating case (aLtErNaTiNg cAsE) and inverse case, which simply flips whatever capitalisation was already there, aren't formal writing or programming conventions at all — they're mostly used for sarcasm and meme text online, most recognisably the “mocking SpongeBob” meme format. Handy to have in a converter, but not something a style guide will ever ask for.

Which one should you use?

Text case styles at a glance
StyleExampleTypical use
Sentence caseConvert your PDF to WordHeadings, UI text, modern style guides
Title CaseConvert Your PDF To WordBook/film titles, some headline styles
UPPERCASECONVERT YOUR PDF TO WORDShort emphasis, acronyms, logos
camelCaseconvertPdfToWordJavaScript/Java variables & functions
PascalCaseConvertPdfToWordClass names, React/UI components
snake_caseconvert_pdf_to_wordPython/Ruby variables, database columns
kebab-caseconvert-pdf-to-wordURL slugs, HTML/CSS attributes
CONSTANT_CASECONVERT_PDF_TO_WORDConstants, environment variables

The simplest rule of thumb: writing for people reading prose calls for sentence case or Title Case; writing for a programming language or a URL calls for whichever of camelCase, snake_case, kebab-case or PascalCase that specific language or platform already expects — consistency with the surrounding code matters more than which one you'd personally pick.

How to convert text between cases

  1. Open Altto's Case Converter.
  2. Paste or type your text.
  3. Pick a case style — the result updates instantly.

It runs entirely in your browser tab, so there's no page reload and nothing sent to a server — every conversion happens locally on your device.

Common questions

What's the difference between Title Case and Sentence case?
Title Case capitalises most of the significant words in a phrase (short joining words like “a”, “and” and “of” are usually treated differently from the rest) and is traditional for headlines and book titles. Sentence case only capitalises the first word and any proper nouns, exactly like a normal sentence — it's the style most modern software interfaces and style guides now prefer for headings, because it reads faster and looks less shouty than Title Case.
Why is camelCase used in programming?
Programming variable and function names usually can't contain spaces, so camelCase (like firstName or getUserData) uses capital letters instead of spaces to keep multi-word names readable while staying a single unbroken token. It's the standard convention for variables and functions in JavaScript and Java; a capitalised variant, PascalCase, is the convention for class and component names in those same languages.
Is typing in ALL CAPS bad for accessibility?
For body text, yes. All-capital text removes the varied letter shapes and ascenders/descenders that make lowercase words fast to recognise by their outline, which slows reading for everyone and is a particular problem for some people with dyslexia or low vision. Some screen readers also read an all-caps word letter by letter, as if it were an acronym, rather than reading it as a normal word. Short labels, acronyms and the occasional emphasised word are fine — long stretches of UPPERCASE body text are the part worth avoiding.
What is snake_case used for?
snake_case joins words with underscores instead of spaces (like first_name or is_available). It's the standard variable and function naming convention in Python and Ruby, and it's also widely used for database column names and configuration keys, because underscores are safe characters in almost every database and file system where a space would cause problems.
Can I convert text case without installing an app?
Yes — Altto's Case Converter runs entirely in your browser tab. Paste or type your text, pick a case style, and the result updates instantly with nothing installed and nothing sent to a server.

Need to convert some text right now?

Altto's Case Converter runs entirely in your browser — free, no sign-up, 11 case styles including camelCase and snake_case.

Open Case Converter