Sentence Case Converter

Turns shouting into readable prose. Capitalises the start of each sentence, leaves acronyms alone, and does not trip over abbreviations like "Dr." or "e.g."

What sentence case actually means

Sentence case is how ordinary prose is written: a capital letter at the start of each sentence, and lowercase everywhere else except proper nouns. It is also the house style for headlines at most British publications and for interface labels in most design systems, which is why it comes up far more often than title case in product work.

The reason people search for a converter is nearly always the same: a paragraph got typed with Caps Lock on, or text was pasted out of a system that stored everything in capitals. Retyping it is tedious. Lowercasing the lot and fixing the sentence starts by hand is almost as bad.

The three things that break naive converters

Abbreviations

The simple approach capitalises the letter after every full stop. That produces "Dr. Smith said e.g. The results were poor" — a capital in the middle of a sentence, because "e.g." ends in a period without ending a sentence. This converter checks the word against a list of common abbreviations (Dr, Mr, Mrs, Prof, St, vs, etc, e.g., i.e., approx, Inc, Ltd and others) and does not treat those as sentence breaks.

Acronyms

Lowercasing everything destroys NASA, HTML, BBC and NHS. With "keep acronyms as typed" switched on, a capitalised word standing on its own is preserved, and so are mixed-case brand names like iPhone and eBay. Switch the option off if you want everything forced to lowercase regardless.

Telling shouting from acronyms

The tricky case is text where both appear. "HELLO WORLD" and "NASA" look identical to a simple rule, but one is shouting and one is a name. The test used here is context: a capitalised word sitting next to other capitalised words is treated as shouting and lowercased, while a capitalised word surrounded by ordinary text is treated as an acronym and kept. And when a passage is mostly capitals to begin with, it is read as Caps Lock and lowercased throughout, acronyms included — because in an all-caps paragraph there is no way to tell them apart.

What it will not do

It cannot capitalise proper nouns it has no way of recognising. If you feed it "dr. lee agreed", you get "Dr. lee agreed" — the sentence start is fixed, the surname is not, because "lee" is also an ordinary word. No converter solves this without a name dictionary, and the ones that claim to are guessing. Read the output before you send it.

Questions

Does it fix the pronoun "I"?

Yes. A standalone "i" becomes "I", and contractions like "i'm", "i've", "i'll" and "i'd" are corrected too.

What about a new line without a full stop?

Each new line starts a new sentence, so lists and bullet points capitalise correctly even where there is no punctuation.

Is my text sent anywhere?

No. The conversion happens in your browser and nothing is uploaded or stored.

Is this the same as Title Case?

No. Sentence case capitalises only the first word of a sentence; title case capitalises most words in a headline. If you need the second, use the title case converter, which follows AP, APA, Chicago and MLA rules.

For UPPERCASE, lowercase, camelCase, snake_case and text clean-up, use the main case converter.