Sentence Case Converter

Capitalize only the first letter of each sentence — and proper nouns. The lowercase-friendly style of modern body text and UI copy.

Input
Output

What is Sentence case?

Sentence case capitalizes the first letter of each sentence and leaves the rest in lowercase, except for proper nouns. It's the everyday capitalization of running prose — the way you write a paragraph.

Compared to title case, sentence case is quieter, less formal, and easier to read at a glance. It's increasingly popular for UI headings, marketing body copy, and friendly product writing where title case feels too shouty.

When to use Sentence case

  • Body paragraphs — virtually all running prose.
  • Modern UI headings — Apple, Google, Microsoft all use sentence case for most interface labels.
  • Captions and figure labels.
  • Subtitles and second-level headings where title case would feel heavy.
  • Friendly marketing copy — sentence case feels conversational, title case feels formal.
  • Academic reference list entries — APA reference lists use sentence case for article and book titles.

How Sentence case conversion works

  1. The very first letter of the input is capitalized.
  2. The first letter after a period, question mark, or exclamation mark followed by whitespace is capitalized.
  3. All other letters become lowercase.
  4. Proper nouns (iPhone, NASA, JavaScript) are restored to their canonical form when the proper-noun dictionary is enabled.

Worked examples

Input Sentence case
hello world. how are you? Hello world. How are you?
THE BIG SHOUT. THIS NEEDS CALMING DOWN. The big shout. This needs calming down.
first sentence. second sentence! third sentence? First sentence. Second sentence! Third sentence?

Related case formats

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