Sentence Case Converter

Sentence case follows the normal capitalization rule for English prose: the first letter after a period, question mark or exclamation point is capitalized, and everything else is lowercased. This is the casing style used in ordinary paragraphs, in contrast to Title Case, which capitalizes the main words of a heading.

The most common reason to use this converter is fixing text that arrived in the wrong case, such as a paragraph typed with caps lock on, text pasted from a source that used all capitals for emphasis, or OCR output that lost its original capitalization. Running it through sentence case restores normal, readable prose in one step.

Because the rule relies on detecting sentence-ending punctuation, an abbreviation like Dr., U.S. or e.g. can be mistaken for the end of a sentence and cause the next word to be capitalized incorrectly. Likewise, since every letter besides the first in each sentence is lowercased, proper nouns and acronyms that should stay capitalized get flattened too and typically need a manual fix afterward.