Case Converter

How to use it

1. Paste your text into the left box.
2. Pick a case. Five text cases on the left, five code cases on the right. One click each.
3. Read the result on the right, then copy or download it.
4. Chain conversions with “Use result as input” if you need to go from one case to another.

Changing the text re-applies whichever case is selected, so you can keep editing without clicking again.

How to convert uppercase to lowercase

Paste the text and press lower case. Every letter folds down, including accented ones, and spacing and punctuation are untouched.

This is the single most-searched version of the task, usually because someone has a block of text that arrived in capitals — a spreadsheet export, a form submission, an email from someone with caps lock on — and needs it readable.

Elsewhere:

How to convert lowercase to uppercase

Press UPPER CASE. Accented characters convert properly — café becomes CAFÉ rather than losing the accent, which some naive converters do.

Worth knowing before you use it on anything long: uppercase text is measurably slower to read. Lowercase letters have distinct shapes — ascenders, descenders, round bowls — and readers use those shapes to recognise words without spelling them out. Capitals are all the same height and strip that cue away. Fine for a heading of three words. Not fine for a paragraph.

Screen readers also treat some all-caps words as initialisms and spell them out letter by letter.

What each case actually is

Title Case and Capitalized Case look identical in that example, on purpose. They diverge as soon as a small word appears in the middle — which is most real titles.

Title Case, done properly

Type “the lord of the rings” into most case converters and you get The Lord Of The Rings. That is not title case. It is every word capitalised, which is Capitalized Case wearing a different label.

Real title case has rules. The tool follows AP and APA, which is the right default for anything published on the web:

• Always capitalise the first word and the last word, whatever they are.
• Lowercase articles: a, an, the.
• Lowercase the coordinating conjunctions: and, but, or, nor, for, yet, so.
• Lowercase prepositions of three letters or fewer: at, by, in, of, off, on, to, up, via.
• Capitalise everything else, including prepositions of four letters or more.
• Capitalise the word after a colon — it begins a new clause.

That last-but-one rule is the one nearly everyone misses.

Chicago and MLA disagree with that rule, and it is the only real split in title case. They lowercase every preposition regardless of length, so where AP writes Gone With the Wind, Chicago writes Gone with the Wind. Neither is a typo. If you are writing for a journal or a publisher, check which one they use; for a web page, AP is the safer default.

If what you actually want is a specific word — is is capitalised, is to, is and — our guide to which words to capitalise in a title has a lookup table of the words people stop on, with both conventions side by side.

Row two is the interesting one. With is a preposition, so people assume it stays lowercase — but it is four letters, so it is capitalised. That is why the film is Gone With the Wind and not Gone with the Wind. Row five shows the last-word rule overriding everything: for is normally lowercase, but it ends the title, so it is capitalised.

The tool above applies all six rules. If you specifically want every word capitalised, that is what Capitalized Case is for.

Changing case in Excel, Word and Sheets

Excel has three case functions and no button. Word has a button and no functions. Neither does title case correctly.

PROPER() is the one that catches people out. It is not title case — it capitalises every word, so you get The Lord Of The Rings, and it also capitalises after any non-letter, which turns o'brien into O'Brien (fine) and ID-4021 into Id-4021 (not fine). Word’s “Capitalize Each Word” has the same behaviour.

That is the gap this tool fills for spreadsheet work: copy the column, paste it here, pick Title Case, paste the result back. It is also why there is no Excel formula in that last row — doing it properly needs a word list, and a formula cannot hold one.

There is no keyboard shortcut for all caps in Excel. In Word it is Ctrl+Shift+A, and Shift+F3 cycles through the three basic cases, which is the shortcut most people are looking for.

Developer cases

Case in code is a convention, not a preference. Using the wrong one is not a style disagreement — in most codebases it is a lint error.

The converters round-trip between all five. Paste camelCaseInput and press snake_case and you get camel_case_input, because the converter splits on capital letters as well as on separators. Paste MAX_RETRY_COUNT and press PascalCase and you get MaxRetryCount.

Two details that catch naive implementations out. Runs of separators collapse, so a b--c__d becomes a_b_c_d rather than producing empty segments. And consecutive capitals are treated as an acronym boundary, so XMLHttpRequest becomes xmlHttpRequest and not xMLHttpRequest.

Worked example

Start with a heading pasted from a spreadsheet:

ANNUAL REPORT ON THE STATE OF THE MARKET

Title Case keeps on, the and of lowercase. Capitalized Case does not. The kebab-case output is a usable URL slug as-is.

The Turkish i problem

Case conversion looks like the most boring operation in computing. It has one famous trap, and it is worth knowing about because it has broken real systems.

In English, the uppercase of i is I. In Turkish and Azerbaijani it is not. Those languages have two separate letters:

So on a computer set to Turkish, lowercasing ID gives ıd, not id. Code that lowercases a string before comparing it to "id" then fails — but only for Turkish users, which is why this class of bug reaches production. It has hit .NET, Java and Android apps often enough to have a name: the Turkish i problem.

This tool uses invariant casing, the English rules, regardless of your system language. That is the right default for the thing people actually paste here — headings, titles, data, code — and it means ID always lowercases to id.

The practical lesson for developers: when you lowercase a string to compare it against a fixed value, ask for the invariant rules explicitly. toLowerCase() in JavaScript and ToLowerInvariant() in C# are safe; toLocaleLowerCase() and a locale-aware ToLower() are not, for that purpose.

Why text arrives in the wrong case

Most people are here because text turned up looking wrong, not because they woke up wanting to convert case. The usual sources:

• Form submissions and CSV exports. Names typed in all caps by users, or normalised to uppercase by a legacy system that stored everything that way.
• Spreadsheet headers. Column names arrive as CUSTOMER_NAME and need to become Customer name for a report, or customerName for code.
• Copy from a design file. A heading styled with CSS text-transform: uppercase looks uppercase but is not — copy it and you get the original lowercase text, or the reverse.
• Caps lock. Still the leading cause.

That third one catches people out regularly. If text looks uppercase on a web page but pastes as sentence case, the capitals were never in the text — they were a style rule. Converting with this tool makes them real.

What this tool leaves out, deliberately

No alternating case, no inverse case, no upside-down text, no Zalgo, no Morse code, no Wingdings. Those exist on other converters and they are the reason those pages feel like an arcade rather than a tool.

There are no ads, nothing to remove ads, no browser-extension prompt, and no account. The text is converted in the page you are reading — nothing is uploaded and nothing is stored.

Things that survive a case change

Converting case changes letters and nothing else. Spacing, line breaks and punctuation come through exactly as they went in.

That includes characters you may not want. Text pasted from Word or Google Docs often carries curly quotes, non-breaking spaces and zero-width characters, and none of them are affected by a case conversion — a common surprise when the “cleaned up” text still breaks a form or a CSV import. The invisible character detector finds and strips them.

If you also need the numbers on a piece of text, the word counter gives words, characters, sentences and pages live. For turning text into a URL-safe value rather than a slug, use the URL encoder.