Convert any text into sentence case — only the first letter of each sentence is capitalised. Useful for cleaning up ALL-CAPS or inconsistent prose.
HELLO WORLD. THIS IS A TEST. how are you? → Hello world. This is a test. How are you?
Sentence case is the standard prose capitalisation rule used in body text: only the first letter of each sentence is capitalised (and proper nouns, which the tool can't always detect automatically). Every other letter is lowercase.
This is the fastest fix for text that arrived in ALL CAPS, in Title Case, or in inconsistent mixed case — paste it in, get back readable prose.
Someone sent you a paragraph in all caps? Paste it in. Sentence case gives you back proper prose without having to retype.
If you paste a Title Case heading into body text, it looks shouty. Convert to sentence case so it reads as a normal sentence.
Modern web style (Apple, Google, Wikipedia, the Guardian) prefers sentence case for headings, not Title Case. The convention scans more conversational and less formal.
Sentence case in email subject lines reads as direct and professional; Title Case looks like marketing copy.
Most modern design systems (Material, Apple HIG, Bootstrap 5) use sentence case for buttons and form labels — "Save changes" not "Save Changes".
The tool processes each sentence independently by splitting on sentence-ending punctuation marks (., !, ?) followed by whitespace. It then lowercases every character in the sentence except the first alphabetic character, which is converted to uppercase. The algorithm does not attempt to detect proper nouns, acronyms, or possessives, so terms like NASA may become Nasa if not handled manually. Unicode sentence segmentation follows UAX #29 break rules for basic punctuation, but the current implementation uses simple regex for speed and is suitable for most standard English text.
Sentence case conversion can be achieved via multiple methods, but this tool offers speed and simplicity without software dependencies.
| This tool | sed command | Word's Change Case | |
|---|---|---|---|
| Accuracy for acronyms | Does not preserve; requires manual fix | Can be preserved if marked as uppercase | Preserves only if explicitly set in autocorrect |
| Handling proper nouns | No detection; all proper nouns lowercased | No detection; fully manual | Improper detection often changes names |
| Speed for large text | Instant client-side processing | Fast but requires command-line knowledge | Slower for very large documents due to formatting |
Sentence case as a typographic convention dates back to the Roman usage of capital letters (majuscules) to mark sentence beginnings and proper nouns, though the modern standard was solidified during the Renaissance with the development of the printing press. The term 'sentence case' in desktop publishing emerged in the 1980s, popularized by word processors like WordStar and Microsoft Word as one of the 'Change Case' options.
No — automated sentence-case converters can't reliably detect proper nouns. The tool capitalises sentence beginnings; you'll need a final pass for names, brands, and place names.
By the punctuation triple . ! ? followed by whitespace. Edge cases (abbreviations like "Dr." or "e.g.") may produce a wrong cap; manually fix anything that looks off after conversion.
No — the tool lowercases everything first, then re-capitalises sentence starts. Run a find-and-replace on " i " to " I " after conversion if you have an English text with the standalone pronoun.
Sentence case for body text, modern UI, and most modern web/digital style. Title Case for traditional book and article titles, AP/Chicago-style headings, and formal print contexts. When in doubt, sentence case is the safer modern default.