Sentence case vs title case: which to use and when
The difference between sentence case and title case, where each one belongs, and how automatic conversion handles names and abbreviations.
What sentence case actually means
Sentence case is the ordinary way we write prose: the first word of each sentence is capitalized, along with proper nouns and the pronoun I, and everything else is lowercase. It is what you read in books, articles and emails because it is easy on the eye and does not shout. This converter produces sentence case by lowercasing the whole input and then raising the first letter of the text and of each new sentence. It deliberately leaves the rest alone so your natural phrasing survives.
How title case differs
Title case capitalizes most words in a phrase, typically every word except short articles, conjunctions and prepositions like a, the, and or of. It is designed for headlines, book titles and headings where a scannable, emphatic look is wanted. Applying title case to a full paragraph would make it hard to read, and applying sentence case to a headline can look under-styled next to other titles. Choosing the right one is really about matching the convention your document or publication already uses.
Where each style belongs
Reach for sentence case in body copy, product descriptions, chat messages, form labels and most user interface text, since it reads quickly and feels calm. Many modern style guides, including several used by large software companies, now favor sentence case even for buttons and headings to keep a friendly tone. Title case still rules for formal article titles, marketing headlines, legal document names and academic references where a publisher or citation style demands it. When in doubt, follow the surrounding text so your capitalization stays consistent.
What automatic conversion can and cannot do
Rule-based conversion is fast and predictable, but it works on punctuation, not meaning. This tool knows a sentence starts after a period, question mark or exclamation mark, and it always fixes the pronoun I, yet it cannot tell a proper noun from a common one, so lowercase names and acronyms stay lowercase. It also treats the period in abbreviations like Mr. or a.m. as a sentence break, which can capitalize the next letter. The practical workflow is to convert first for the bulk of the fix, then skim the result to correct names and abbreviations by hand.