Sentence Case Converter
Transform your text to proper sentence case where only the first letter of each sentence is capitalized. Our sentence case converter normalizes improperly formatted text, making it readable and professional for emails, documents, and web content.
Sentence Case Rules
| Element | Capitalization | Example | First word of sentenceUppercase"The meeting starts..." Proper nounsUppercase"...at Google headquarters." AcronymsUppercase"The CEO attended." All other wordsLowercase"...was very productive." After periodUppercase"It ended early. Everyone left." | After question mark | Uppercase | "Did you go? I did." |
Sentence Case Converter Logic
``javascript
function toSentenceCase(text) {
// Convert all to lowercase first
let result = text.toLowerCase();
// Capitalize after sentence endings (. ! ?)
result = result.replace(/(^|[.!?]\s+)([a-z])/g,
(match, separator, letter) => separator + letter.toUpperCase()
);
// Handle "I" as special case (always capitalize)
result = result.replace(/\bi\b/g, 'I');
return {
original: text,
sentenceCase: result,
sentenceCount: (text.match(/[.!?]+/g) || []).length + 1
};
}
console.log(toSentenceCase("HELLO WORLD. HOW ARE YOU TODAY?"));
// Output: "Hello world. How are you today?"
``
When to Use Sentence Case
Sentence case is the standard for body text, paragraphs, and most written communication. Many style guides now recommend sentence case for headings as well—it's easier to read and appears less formal than title case. The New York Times, The Guardian, and many modern websites use sentence case for article headlines.
Handling Proper Nouns
Our basic converter cannot identify proper nouns (names, places, brands) that should remain capitalized. After conversion, manually check for "microsoft" → "Microsoft", "john" → "John", and similar proper nouns that require capitals regardless of position in the sentence.