Sentence Case Converter

Formula

How this is calculated

Sentence case follows the most natural writing convention: the first word of every sentence starts with a capital letter; all other words are lowercase unless they are proper nouns (which this tool cannot detect automatically). The converter works in three steps: first it lowercases the entire text; then it scans for sentence boundaries — a period (.), exclamation mark (!), or question mark (?) followed by whitespace — and capitalises the first letter after each; finally it capitalises the very first character of the whole text regardless of punctuation.

A common edge case is the first-person pronoun "I", which should always be uppercase in English. The converter restores every standalone lowercase "i" (surrounded by word boundaries) to "I". Other proper nouns — names, places, brands — remain lowercase because distinguishing them from common nouns requires contextual knowledge beyond simple pattern-matching. Review the output and re-capitalise proper nouns manually.

The stat panel shows character count, word count, estimated sentence count, and how many characters were changed — useful for verifying that the conversion did what you expected.