Sentence Case Converter

It works in two steps. First every letter is lowercased. Then a capital is put back in two places only:

• the first letter of the whole text, even after leading spaces;
• the first letter after a sentence end, meaning a full stop, a question mark or an exclamation mark, as long as a space or line break comes next.

Decimals are safe, because a full stop followed directly by a digit isn't a sentence end: it costs $5.50 today. ok becomes It costs $5.50 today. Ok.

Here is a shouted notice and what the converter returns:

WHERE IS THE MEETING? IT STARTS AT 10 A.M. IN ROOM 4B.

Where is the meeting? It starts at 10 a.m. In room 4b.

Most of it is right, but two things need fixing:

1. In got a capital because a.m. ends with a full stop and a space, which looks like a sentence end. Abbreviations such as Dr., Mr., e.g. and etc. cause the same false capital on the next word.
2. 4b lost its capital. So does every name, place, acronym and the word I in the middle of a sentence: yes i know what i said stays lowercase apart from the first Y.

A sentence like Our office in Paris opens at 9. Ask for Maria. comes back as Our office in paris opens at 9. Ask for maria., so proper nouns always need a second look.

A line break on its own doesn't start a new sentence. That has three effects worth knowing:

• A list of headings only gets one capital. SHIPPING POLICY, RETURNS AND REFUNDS and CONTACT US on separate lines come out as Shipping policy, returns and refunds and contact us. Convert headings one at a time, or capitalise the first letter of each line yourself.
• Bullets written as - first item stay lowercase, because the dash comes before the first letter.
• A quote mark at the very start blocks the first capital the same way: “quoted start” and more keeps a lowercase q.

Text that begins with an accented letter such as é isn't capitalised either, and neither is the word after a question mark with no space, as in what?no.

Sentence case is the usual choice for body text, button labels, form hints and many web headings, because it reads like normal writing. Title case suits book titles and formal headlines. If you are cleaning up text that arrived in capitals, sentence case gets you closer to finished prose in one step than lowercasing, and needs fewer manual fixes than title case.