What is sentence case?
Sentence case means capitalizing only the first letter of each sentence and any proper nouns — everything else stays lowercase. It is the default style for most online publishing: Google, BuzzFeed, The Guardian, and the APA style guide all use it for headlines, because lowercase words are easier and faster to read than Every Word Being Capitalized.
This converter applies the rule automatically. Paste text in ANY casing — ALL CAPS, Title Case, or a messy mix — and it lowercases everything, then capitalizes the first letter after every period, question mark, and exclamation point, plus the first letter of each line. “HELLO WORLD. this is NEXT.” becomes “Hello world. This is next.” in one pass.
Sentence case vs. title case
The two styles solve different problems. Title case (capitalize principal words) is traditional for book titles, legal documents, and formal headlines. Sentence case is friendlier for web headlines, table headers, email subject lines, and UI buttons — and it is far more forgiving, because you never have to remember whether “through” or “beneath” counts as a long preposition.
You can compare both styles on the same text right here: paste your headline, click Sentence case, then click Title Case, and pick the version that matches your style guide. Copy whichever wins.