Sentence Case Converter
Capitalize the first letter of each sentence while keeping the rest of the text lowercase.
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About Sentence Case Converter
Sentence case capitalizes the first letter of each sentence and the personal pronoun 'I'; everything else stays lowercase. It's the form most paragraphs of running prose use. This converter detects sentence boundaries at periods, question marks, and exclamation marks followed by whitespace.
When to use it
- Normalizing the case of paragraphs pasted from sources with inconsistent capitalization
- Calming down a shouty all-caps message into readable prose
- Preparing body text for a CMS that doesn't auto-capitalize sentences
- Producing consistent transcript text from speech-to-text output
How it works
The input is fully lowercased. Then every position that follows the start of the string or a sentence-terminating punctuation mark plus whitespace gets its next letter promoted to uppercase. The result preserves punctuation, line breaks, and word spacing.
Examples
Each new sentence gets a single capital
HELLO WORLD. ARE YOU READY? LET'S GO!
Hello world. Are you ready? Let's go!
Frequently asked questions
- Does it handle 'i' as a pronoun?
- No. Detecting 'I' as a pronoun versus a lowercase letter requires natural-language understanding. After conversion, do a find-replace of ' i ' → ' I ' (and similar edge cases) if needed.
- What counts as a sentence boundary?
- A period, exclamation mark, or question mark followed by whitespace. Sentences without trailing punctuation (typical of bullet lists) are treated as one long sentence.
- Will it preserve proper nouns?
- No. Proper nouns get lowercased along with everything else. For prose with many proper nouns, sentence-case is a starting point, not a final result.