“open the file. check the header. save it again.” — Uppercase, Lowercase, Title Case and Sentence Case
Enter this string in the converter and these are the four outputs it returns. Nothing here is stored or guessed: the same regular expressions that run in your browser were run at build time, so the page and the tool agree character for character.
Where each form belongs
| Form | Result | Typical use |
|---|---|---|
| UPPERCASE | OPEN THE FILE. CHECK THE HEADER. SAVE IT AGAIN. | Loud labels, ticker codes, shouting about a deadline |
| lowercase | open the file. check the header. save it again. | Email addresses, URL slugs, file names |
| Title Case | Open The File. Check The Header. Save It Again. | Headlines, button labels, menu items |
| Sentence case | Open the file. Check the header. Save it again. | Body copy, descriptions, help text |
How the rules behave on this string
Every conversion starts from the same tidy-up: runs of spaces collapse to one and the ends are trimmed, while line breaks are preserved. Uppercase and lowercase then apply directly. Sentence case lowercases everything and re-capitalises the first letter after a full stop, question mark, exclamation mark or line break. Title case lowercases everything and re-capitalises the letter that follows the start of a line, a space, a quote, a bracket or an apostrophe.
Title Case here is a blanket rule: every word gets a capital, including the short ones. Writers who follow AP or Chicago style would leave of, the and and lowercase in a headline, so the Title Case line above is a starting point rather than a finished house style.
Before any conversion runs, the string measures 47 characters and 9 words; the letter-to-punctuation split is 36 to 11, and the vowels number 16, or 44% of the letters. The longest token, “header.”, carries 7 characters against 2 in “it”, against an average of 4.0. Entry 47 of 76, it produces 9 capitals in Title Case — 25% of its letters.
Similar strings
Frequently asked questions
What does each of the four results mean?
They are four separate passes over the same 47-character string. UPPERCASE and lowercase are the obvious ones. Title Case capitalises the first letter of every word, and Sentence case capitalises only the first letter of each sentence while forcing everything else down. The converter on the homepage builds them with the identical rules.
Which one should I paste into my document?
Body text should stay in Sentence case: capital at the start of each sentence, lowercase everywhere else. That is the form that survives editing and screen readers alike, and it is the one this page puts in the fourth field.
Converting a whole paragraph, a JSON key list or a batch of headlines? The CaseLabNow case converter takes free text up to several thousand characters, and the case reference library has a page for every string listed here.