Sentence Case Converter
Convert text to sentence case: the first letter of each sentence is capitalized and the rest is lowercase, keeping acronyms like NASA. Also splits identifiers.
Example: THE QUICK FOX. IT RUNS → The quick fox. It runs
Each line is converted separately. Words are split at spaces, punctuation, _ - . / and camelCase boundaries; acronyms such as XML stay together and digits stay attached to the previous word.
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View AllWhat is Sentence case?
The Sentence case converter lowercases text and capitalizes the first letter of every sentence, which is the most natural way to fix TEXT WRITTEN IN ALL CAPS or random capitalization. Identifiers such as userAccountId are split into words first (User account id).
How to use Sentence case
- Type or paste text into the Input box (or click Load sample).
- The converted text appears instantly in the Output box.
- Click Copy to copy the result.
Example
HELLO WORLD. BYE NOW
Hello world. Bye now
When to use Sentence case
Use it to fix shouting text, normalise headings to sentence style, or turn identifiers into readable labels. Proper nouns (names, places) cannot be detected and will be lower-cased – review the result. For headline-style capitalisation use Title Case.
How Sentence case works
Each line is processed as a sequence of words and punctuation. A new sentence starts at the beginning of the text, after an empty line and after ., !, ? or …; the first letter of that sentence is upper-cased and other words are lower-cased. Words written entirely in capitals (acronyms like NASA) and mixed-case brand names (iPhone) are kept as-is, unless the whole line is in capitals – then everything is lower-cased first. The English pronoun "i" is written as "I". A line with no spaces that looks like an identifier (userAccountId, user_account_id) is split into words first.
Common Use Cases
- Fixing text typed with Caps Lock on
- Converting UI labels to sentence-style capitalisation
- Turning variable names into readable labels
- Cleaning up imported data with inconsistent capitalisation
Security Note
Everything runs locally in your browser; the code you paste is not uploaded.
FAQs
Why was a name lower-cased?
Proper nouns cannot be recognised automatically; capitalise them manually.
Why is NASA kept in capitals?
All-caps words in mixed-case text are treated as acronyms. If the whole line is in capitals, everything is lower-cased instead.
Does it work for other languages?
Yes for any script with upper and lower case; the "I" rule only matters for English.