Text Case Converter — Uppercase, Lowercase, Title Case and More Explained
Text case conversion is something developers, writers, marketers, and data teams do dozens of times a week — fixing inconsistent capitalisation in exported data, formatting titles correctly, converting database field names between naming conventions, or preparing content for different platforms. Doing it manually for anything more than a sentence is tedious and error-prone. A case converter handles it in one click.
Convert text between any case format instantly with our free Case Converter tool. For counting characters in your converted text, use our Character Counter. For removing duplicate lines from formatted data, our Duplicate Lines Remover pairs well with case conversion workflows.
The Main Case Formats and When to Use Each
UPPERCASE
Every letter is capitalised. ALL CAPS is used for: acronyms and abbreviations (NASA, HTML, API), emphasis in informal contexts, legal document headings and definitions, warning labels, and keyboard key names (CTRL, ALT, DELETE). In email and online communication, ALL CAPS is widely interpreted as shouting — use it sparingly in body text. For data processing, UPPERCASE is often used to normalise field values before comparison to avoid case-sensitivity issues.
lowercase
Every letter is lowercase. Used for: URL slugs, CSS class names, HTML attributes, email addresses, Unix filenames and command names, and database column names in many conventions. Lowercase is also the default for most programming identifiers in languages like Python. For SEO specifically, URL slugs should always be lowercase — our Slug Generator generates properly formatted lowercase slugs from any title.
Title Case
The first letter of each major word is capitalised. Minor words — articles (a, an, the), coordinating conjunctions (and, but, or), and short prepositions (in, on, at, by) — are usually lowercase unless they appear as the first or last word. Title case is used for: article headlines, book and film titles, product names, page headings, and any heading in formal documents. Different style guides (AP, Chicago, APA, MLA) have slightly different rules for which words to capitalise.
Sentence case
Only the first letter of the sentence is capitalised, plus proper nouns. This is how normal sentences are written in body text. Many modern brands and user interfaces have moved toward sentence case for headings and button labels — it feels more conversational and is easier to read than title case for longer phrases. Google's Material Design guidelines recommend sentence case for most UI text.
camelCase
The first word is lowercase, subsequent words start with uppercase, no spaces. Used for: JavaScript variable names (myVariableName), JSON property keys, and many programming languages. lowerCamelCase (starting lowercase) is the most common variant. UpperCamelCase (also called PascalCase, starting uppercase) is used for class names in most object-oriented languages.
snake_case
Words are all lowercase, separated by underscores. Used for: Python variable and function names, database column names, file names in many Unix conventions, and REST API field names in many APIs. SQL column names are conventionally snake_case. The choice between camelCase and snake_case is often determined by language convention — Python uses snake_case, JavaScript uses camelCase.
kebab-case
Words are all lowercase, separated by hyphens. Used for: URL slugs, HTML attribute names, CSS class names, and file names in web projects. "kebab-case" is the preferred format for anything that will appear in a URL, because hyphens are word separators in Google's index while underscores are not.
Convert text to any case format instantly — uppercase, lowercase, title case, camelCase and more
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JavaScript
"hello world".toUpperCase() gives "HELLO WORLD" "HELLO WORLD".toLowerCase() gives "hello world" For title case, there is no built-in method — you need a custom function or library like lodash's _.startCase(). For camelCase conversion: lodash provides _.camelCase("hello world") giving "helloWorld".
Python
"hello world".upper() gives "HELLO WORLD" "HELLO WORLD".lower() gives "hello world" "hello world".title() gives "Hello World" (capitalises after any non-letter, including apostrophes — "it's" becomes "It'S" which is a known quirk) "hello world".capitalize() gives "Hello world" (only first character capitalised)
CSS
text-transform: uppercase converts display to uppercase without changing the underlying HTML. text-transform: lowercase converts display to lowercase. text-transform: capitalize converts the first letter of each word to uppercase. This is display-only — the actual HTML content is unchanged. Screen readers read the original text, not the transformed display.