The four case styles explained
A case converter switches the capitalization pattern of a block of text without changing the words themselves. This tool offers four modes. UPPERCASE turns every letter into a capital, useful for headlines, warning labels, or acronyms you want to stand out. lowercase does the opposite, turning every letter small — handy for normalizing usernames, slugs, or text that was typed with the caps lock key stuck on. Title Case capitalizes the first letter of most words while keeping short connecting words lowercase, the style used for headlines and book titles. Sentence case capitalizes only the first letter of each sentence, the way ordinary prose is written. Switching between uppercase to lowercase and back is instant — pick a mode, and the output box updates immediately from whatever is in the input box, with no button to click.
Title case rules this tool follows
Of the four modes, title case is the one with real rules behind it, and it's worth knowing exactly what this title case converter does. First, it lowercases the entire input, then it walks through each word and capitalizes the first letter — except for a fixed list of small words, which stay lowercase unless they happen to be the very first or very last word in the text. Those small words are: a, an, and, as, at, but, by, for, if, in, nor, of, on, or, per, so, the, to, up, via, and yet. So "the lord of the rings" becomes "The Lord of the Rings" — "the" is capitalized at the start because it's the first word, "of" and "the" stay lowercase in the middle, and the last word is always capitalized regardless of what it is. One side effect worth knowing: title case rebuilds the text by splitting it on whitespace and rejoining the words with single spaces. That means any line breaks inside your input disappear in title mode, and any extra spacing — double spaces, leading or trailing blanks — gets collapsed to one space between words. If you need to keep your paragraph structure intact, use uppercase, lowercase, or sentence case instead, since all three of those preserve line breaks exactly as you typed them.
How to use it
Paste or type your text into the box on the left. Pick a case style using the four radio buttons above the text boxes — Title Case is selected by default. The output box on the right recalculates the moment you type, paste, or switch modes, so there's nothing to submit and nothing to wait for. Once the result looks right, click Copy to send it straight to your clipboard, or click Clear to empty the input and start fresh. Everything happens locally in your browser using plain JavaScript: nothing you type here is uploaded, logged, or sent to a server, which makes this a reasonable sentence case converter even for drafts or anything else you'd rather not run through a random website, the same as any of the other three modes.
When to use each case style
Different situations call for different case styles. UPPERCASE fits short, attention-grabbing text: button labels, warning banners, or matching a brand's all-caps logo treatment. lowercase is the right call when you're cleaning up usernames, file names, hashtags, or any text that needs to match a system that's case-sensitive and expects lowercase input. Title Case belongs in headlines, article titles, book and movie names, and navigation menus, anywhere a reader expects the traditional capitalize-the-important-words convention. Sentence case is the safest default for body text and prose — it's also the fastest way to rescue text that got typed or pasted in ALL CAPS, since it lowercases everything first and then capitalizes just the start of each sentence. Keep in mind that this sentence case converter has no dictionary of proper nouns or acronyms, so a name like NASA or a product like iPhone will lose its original capitalization along with the rest of the all-caps text and won't be automatically restored — you'll need to fix those by hand afterward. For anything sensitive, all four modes run entirely client-side, so you can convert case as often as you like without anything leaving your browser.