Sentence Case Converter — Fix Your Capitalization

What Is Sentence Case?

Sentence case is the standard capitalization style used in everyday writing. It capitalizes only the first letter of the first word in a sentence, plus any proper nouns. Everything else remains lowercase. For example, "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG" becomes "The quick brown fox jumps over the lazy dog."

This is the most natural and readable capitalization style. It's how we write paragraphs, emails, text messages, product descriptions, and most content on the web.

When to Use Sentence Case

• Body text and paragraphs — All standard writing uses sentence case. It's the default for books, articles, blog posts, and web content.
• Fixing caps lock text — If you accidentally typed with caps lock on, paste your text here to instantly restore proper sentence capitalization.
• UI and product design — Google, Apple, and Microsoft all recommend sentence case for button labels, menu items, and interface text in their design guidelines. It feels more conversational and modern.
• Social media posts — Sentence case reads naturally and approachably on social platforms.
• Email body text — Emails should use sentence case for the message body to maintain readability and a professional tone.
• Subtitles and descriptions — Video subtitles, image captions, and product descriptions all use sentence case.

How Sentence Case Differs from Other Formats

Here's how the same text looks in each case format:

How This Tool Works

The sentence case converter processes your text in three steps:

1. Converts all text to lowercase — This removes any existing capitalization.
2. Capitalizes the first character — The very first letter of the text is made uppercase.
3. Capitalizes after sentence endings — Any letter following a period (.), exclamation mark (!), or question mark (?) followed by a space is capitalized, starting a new sentence.

The conversion happens entirely in your browser. Your text is never uploaded to a server, so it stays completely private. The tool handles up to 15,000 characters at a time.

Note: This tool uses a simple algorithm that capitalizes after sentence-ending punctuation. It does not detect proper nouns (like names of people, places, or brands), so you may need to manually capitalize those after conversion.

Sentence Case in Style Guides

Modern style guides and design systems increasingly recommend sentence case over title case:

• Google Material Design — Uses sentence case for all button text, labels, menu items, and headers within apps.
• Apple Human Interface Guidelines — Recommends sentence case for most UI text except navigation bar titles.
• Microsoft Fluent Design — Uses sentence case for body text, tooltips, and most interface elements.
• Web Content Accessibility Guidelines (WCAG) — While not requiring a specific case, sentence case improves readability for people with reading difficulties and cognitive disabilities.

The trend across the tech industry is clear: sentence case is the modern standard for user interfaces because it feels friendlier, is easier to read, and creates a more conversational tone.