About the Case Converter
This free case converter changes the capitalisation of your text. Paste it in and switch to UPPERCASE, lowercase, Title Case, Sentence case, camelCase, PascalCase, snake_case or kebab-case with one click.
Everything runs in your browser — nothing is uploaded. That matters more than it sounds, because the text people need to re-case is often a column of customer names, a list of email addresses or a database export.
The cases, and when each one is right
UPPERCASE — every letter capital. Good for short labels and acronyms. Bad for anything longer than a few words: capitals remove the shape of a word, and readers identify words partly by outline, so a sentence in caps is measurably slower to read. Screen readers sometimes spell long capitalised words out letter by letter, and in a message it reads as shouting.
lowercase — everything small. Useful for normalising data before comparing it, and for tags, slugs and email addresses.
Sentence case — first letter of the sentence capital, the rest as written. This is ordinary prose, and increasingly the standard for headings and UI labels too, because it is easier to read and easier to translate.
Title Case — Most Words Capitalised. Traditional for headlines and book titles in English. The catch is that the exact rules depend on which style guide you follow.
camelCase — firstNameField. Words joined with no spaces, each new word capitalised except the first. The standard for variables and functions in JavaScript, Java and C#.
PascalCase — FirstNameField. Same idea but the first word is capitalised too. Used for class and component names in most languages, including React components.
snake_case — first_name_field. Words joined by underscores. The standard in Python and Ruby, and near-universal for SQL column names.
kebab-case — first-name-field. Words joined by hyphens. Used for URLs, CSS classes, HTML attributes and filenames — anywhere a hyphen is safe but an underscore is awkward.
Why Title Case is harder than it looks
Two style guides, two different results for the same headline.
The problem is deciding which small words stay lowercase. Under AP style, words of three letters or fewer stay lowercase unless they begin or end the title. Under Chicago style, articles (a, an, the), coordinating conjunctions (and, but, or) and all prepositions stay lowercase regardless of length — so Between stays lowercase in Chicago but is capitalised in AP.
Both agree on two things: capitalise the first and last word, always, and capitalise everything else that is not on the list.
Then there are words no automatic converter can get right, because they need to know what you meant. iPhone must keep its lowercase i. eBay, macOS, PhD, NASA and iOS all have fixed shapes. Any converter will flatten some of them, so a title-cased headline always deserves a human read before it ships.
Why programming has so many cases
It looks like pointless tribalism. It is not — it is because identifiers cannot contain spaces, so every language had to pick a way of joining words, and the choice stuck.
Where each one lives today:
- JavaScript / TypeScript — camelCase for variables and functions, PascalCase for classes and React components, kebab-case for filenames and CSS
- Python — snake_case for variables and functions, PascalCase for classes
- Java / C# — camelCase for variables, PascalCase for classes and methods
- SQL — snake_case for tables and columns, because many databases fold unquoted names to lowercase anyway
- CSS / HTML — kebab-case throughout
- Constants — UPPER_SNAKE_CASE in nearly every language
- URLs — kebab-case, because search engines treat hyphens as word separators and underscores as joiners
The practical value of a converter is moving between them: a snake_case database column becomes a camelCase JavaScript property in a hundred places, and doing it by hand is where typos come from.
The Turkish i, and other traps
Changing case is not always reversible, and occasionally not even safe.
The dotless i. In Turkish and Azerbaijani, uppercase I lowercases to ı (no dot), and i uppercases to İ (with a dot). Lowercasing a string on a Turkish system and comparing it to "identifier" has broken real software — it is a well-known enough bug to have a name.
German ß. The uppercase of ß was historically SS, so STRASSE lowercased does not give you straße back. The capital ẞ exists now but is not universally used.
Acronyms are destroyed by lowercasing. NASA becomes nasa, and no converter can restore it, because it cannot tell an acronym from a shouted word.
Case-insensitive is not universal. Domain names are case-insensitive; the path after them is not — /About and /about can be two different pages. Email is the same: the domain half is case-insensitive, the part before the @ technically is not, though most providers treat it as though it were.
How to use it
- Type or paste your text in the box
- Click a case button to convert it
- Copy the result
Good to know
- Converting to lowercase loses information permanently. Capitals in names and acronyms cannot be recovered afterwards. Keep the original if you may need it.
- Title Case needs a human check for iPhone, eBay, macOS, PhD and every other fixed-shape word.
- Sentence case is winning for headings. Most modern style guides now prefer it — it reads faster and survives translation better.
- Avoid ALL CAPS for anything long. It is slower to read, it can confuse screen readers, and in a message it reads as shouting.
- Use kebab-case in URLs, not snake_case. Search engines split on hyphens; underscores join words together.
- Check accented characters survived. A converter that is not Unicode-aware will mangle é, ü and ñ. This one handles them correctly.
Common questions
What is the difference between Title Case and Sentence case?
Sentence case capitalises only the first word, as in ordinary writing: "How to convert text case". Title Case capitalises most words: "How to Convert Text Case". English headlines and book titles traditionally use Title Case, but Sentence case is now preferred by most product and documentation style guides because it reads more quickly and translates more cleanly.
What is camelCase and how is it different from PascalCase?
Both join words with no spaces and capitalise each new word. camelCase leaves the first word lowercase (firstName); PascalCase capitalises it too (FirstName). By convention camelCase names variables and functions, while PascalCase names classes, types and React components.
Which case should I use for a URL?
kebab-case — lowercase words joined by hyphens, like /free-online-tools. Google treats a hyphen as a word separator and an underscore as a joiner, so image_resizer can be read as one word while image-resizer is read as two. Lowercase matters too, since a URL path is case-sensitive on most servers.
Which case should I use for a database column?
snake_case is the near-universal convention: first_name, created_at. It suits the way most databases fold unquoted identifiers to lowercase, and avoids needing quotes around names. You then usually convert to camelCase in the application layer, which is one of the commonest reasons to reach for a converter.
Why do some words come out wrong in Title Case?
Because the converter cannot know what the word is. iPhone, eBay, macOS and NASA have fixed shapes that no capitalisation rule predicts. Style guides also disagree on which short words stay lowercase — AP keeps words of three letters or fewer lowercase, Chicago keeps articles, conjunctions and prepositions lowercase whatever their length. Always read a title-cased headline before publishing it.
Is my text sent to a server?
No. The conversion happens entirely in your browser, so nothing you paste leaves your device and nothing is stored. Since people often re-case exported customer lists and email addresses here, that is worth knowing.
Related tools
- Word Counter — count words, characters and reading time
- Find and Replace — bulk edits across a block of text
- Remove Extra Spaces — tidy up spacing after a paste
- Remove Duplicate Lines — clean a list before or after re-casing it
