Sentence Case Converter

Sentence case capitalizes just two things: the first letter of each sentence and any proper nouns inside it. Everything else stays lowercase. "My dog ran to the park in Boston" is a sentence-case example — only "My" and "Boston" get a capital letter. It's the same convention you already use when writing a normal sentence, which is where the name comes from. Paste your text into the box above and it converts automatically.

What are the rules of sentence case?

There are really only four things to keep track of:

• The first letter starts capitalized — for a sentence, a heading, or a title.
• Proper nouns stay capitalized — people's names (Marie Curie), places (New York), organizations (NASA), and other specific, named things.
• A new sentence gets a fresh capital — right after a period, exclamation point, or question mark.
• Everything else drops to lowercase — regular nouns, verbs, adjectives, all of it.

Take the sentence "The engineers flew to Chicago for the product launch." Only "The" (it opens the sentence) and "Chicago" (a place name) get capitals — the rest is lowercase.

What is an example of sentence case?

A few before-and-after examples make this easier to see:

• "WHY YOUR EMAILS AREN'T GETTING REPLIES" → "Why your emails aren't getting replies"
• "The Founder Of Netflix Gave A Keynote Speech" → "The founder of Netflix gave a keynote speech"
• "an intro to javascript promises and async code" → "An intro to JavaScript promises and async code"

In each case, proper nouns (Netflix, JavaScript) and the sentence's opening word keep their capital letters, while ordinary words fall back to lowercase.

Where does sentence case show up in style guides?

A handful of well-known style guides call for sentence case specifically:

• APA Style calls for sentence case on titles inside reference lists and bibliography entries.
• The AP Stylebook favors sentence case for news headlines.
• The BBC's newsroom style runs sentence case across the board for headlines.
• Microsoft's writing guidelines call for sentence case in interface labels, headings, and page titles.
• Google's developer documentation style uses sentence case throughout its headings and titles.

A lot of newer websites and products lean toward sentence case too — it just reads more like natural writing and less like a formal headline.

Sentence case vs. title case — what's the difference?

Sentence case: capitalizes the opening word and proper nouns only. Example: "How to speed up your site's page load time"

Title case: capitalizes most of the significant words. Example: "How to Speed Up Your Site's Page Load Time"

Sentence case tends to read as casual and conversational, which is why you'll see it a lot in blog posts, social captions, and marketing emails. Title case leans more formal — think academic papers, newspaper mastheads, and book titles. Which one fits depends on the tone you're going for.

Sentence case vs. upper case — what's the difference?

Sentence case only capitalizes the first word and any proper nouns: "The meeting starts at noon."

Upper case capitalizes every single letter: "THE MEETING STARTS AT NOON."

Upper case tends to show up for acronyms (NASA, HTML), short callouts, or emphasis, while sentence case is what you'd actually want for readable paragraphs and most headings. Long stretches of all-caps text get harder to read the longer they run, so it's generally best kept short.

What mistakes do people usually make with sentence case?

A few of these trip people up more than you'd expect:

• Capitalizing right after a colon: "One rule matters most: consistency" is correct — the word after a colon usually doesn't get capitalized (some style guides differ, so check yours).
• Lowercasing stylized brand names: names like iPhone, eBay, and PayPal keep their official capitalization no matter where they land in a sentence.
• Rewriting acronyms as regular words: NASA, BBC, and HTML don't change — they keep their normal capitalization inside sentence case.
• Missing a proper noun: people, places, and named things always get a capital, wherever they fall: "The concert is happening in Seattle next Friday."

Does this tool recognize proper nouns and abbreviations automatically?

Yes — there's a built-in list of commonly used proper nouns and abbreviations that gets checked after the standard sentence-case rules are applied. That's how terms like NASA, iPhone, JavaScript, PostgreSQL, and place names like New York or Washington end up with their correct capitalization instead of being flattened to lowercase.

That list can't cover everything, though — less common names or specialized terms might slip through with default lowercase capitalization. If that happens, you can fix it by hand afterward, or add the term as a custom entry under Settings so it's remembered next time.

Sentence case vs. plain lowercase — what's the difference?

Lowercase is the simpler of the two: every letter goes lowercase, no exceptions at all. Sentence case is more selective — it capitalizes just the start of each sentence and leaves the rest lowercase, which is what makes it read like ordinary written English. "THE QUICK BROWN FOX" becomes "the quick brown fox" under lowercase, but "The quick brown fox" under sentence case. Reach for plain lowercase when you need uniform lowercase text — CSS class names, URL slugs, that kind of data normalization. Reach for sentence case when the text needs to actually read naturally.

Last reviewed: August 2026