Sentence Case Rules — When to Capitalize Only the First Word

Sentence case is the default capitalization style for modern digital interfaces. Google, Apple, and Microsoft all recommend it for buttons, menus, and labels. If you write UI copy, email subjects, or blog subheadings, you need to know exactly when sentence case applies and how it differs from title case.

What Is Sentence Case

Sentence case capitalizes only the first word and proper nouns, leaving everything else lowercase. It matches how you write a regular English sentence — hence the name.

Examples: "How to write better headlines", "Upload your file here", "Sign in to your account".

Sentence case is the standard for:

• UI elements — buttons, labels, menu items, tooltips, error messages
• Subheadings in blogs and documentation
• Email subject lines (increasingly preferred over title case)
• Social media posts
• Product descriptions and feature lists

It reads naturally because it mirrors ordinary prose. Readers process it faster than title case because there are fewer visual interruptions from capital letters.

Sentence Case Rules Step by Step

Rule 1: Capitalize the first word. Always. Regardless of what the word is — even articles ("A new feature"), prepositions ("In this guide"), or conjunctions ("But first, a warning").

Rule 2: Capitalize proper nouns. Names of people, companies, products, places, and specific technologies keep their standard capitalization. "Set up your Google account" — Google stays capitalized. "Deploy to Amazon Web Services" — the brand name keeps its caps.

Rule 3: Lowercase everything else. Articles (a, an, the), prepositions (in, on, at, for), conjunctions (and, but, or), and common nouns all stay lowercase unless they are the first word.

Rule 4: After a colon, it depends. Style guides disagree here. AP style capitalizes the first word after a colon if what follows is a complete sentence. Chicago style always capitalizes after a colon in titles. For UI copy and digital writing, the safest approach is to capitalize after a colon only when a complete sentence follows.

Rule 5: Hyphenated words. In sentence case, only capitalize the first element of a hyphenated word if it appears at the start. "Self-service portal" becomes "Self-service portal" (not "Self-Service portal"). Proper nouns within hyphenated words keep their caps: "Non-Google alternatives".

Rule 6: Acronyms stay uppercase. "Connect your API key", "Enable HTTPS redirects", "Set the DNS records" — acronyms are not proper nouns, but they maintain their conventional all-caps styling in sentence case.

How FlipMyCase Helps

Converting headlines between title case and sentence case manually means scanning every word and deciding whether it should be capitalized. The case converter at FlipMyCase handles sentence case conversion instantly.

Paste a title case headline like "How To Write Better Headlines For Your Blog" and convert it to sentence case with one click: "How to write better headlines for your blog". The tool processes multiple lines at once, making it practical for batch-converting headers during a site-wide style migration.

Use flipmycase.com to switch between sentence case, title case, UPPERCASE, lowercase, and more — no signup, no limits.

Sentence Case vs Title Case

The choice between sentence case and title case depends on context and style guide.

UI and UX copy: sentence case wins. Google's Material Design guidelines, Apple's Human Interface Guidelines, and Microsoft's Fluent Design all recommend sentence case for buttons, labels, menus, and dialog text. The reasoning: sentence case is easier to scan, feels less formal, and reduces cognitive load. Users process "Create new project" faster than "Create New Project".

Headlines and article titles: style guide dependent. AP style uses title case for headlines. Chicago Manual of Style allows both. APA style uses title case for reference titles but sentence case for headings within a paper. Most blogs and content sites use title case for main titles and sentence case for subheadings.

Email subject lines: trending toward sentence case. Marketing email data consistently shows sentence case subject lines performing comparably to title case, with some studies showing higher open rates. Sentence case feels more personal and conversational, like a message from a person rather than a brand.

Academic writing: varies by discipline. APA uses sentence case for article titles in reference lists. MLA and Chicago use title case. Always check the relevant style guide.

Real-World Examples

Headlines converted from title case to sentence case:

| Title Case | Sentence Case | |---|---| | How To Write Better Headlines For Your Blog | How to write better headlines for your blog | | 10 Tips For Improving Your Code Reviews | 10 tips for improving your code reviews | | The Complete Guide To CSS Grid Layout | The complete guide to CSS Grid layout | | What Every Developer Should Know About REST APIs | What every developer should know about REST APIs |

UI elements in sentence case:

• Button: "Save changes" (not "Save Changes")
• Menu item: "Account settings" (not "Account Settings")
• Error: "Something went wrong. Please try again." (not "Something Went Wrong")
• Tooltip: "Click to copy to clipboard" (not "Click To Copy To Clipboard")

Email subjects in sentence case:

• "Your order has shipped" (not "Your Order Has Shipped")
• "3 new features you should try" (not "3 New Features You Should Try")
• "Quick question about your project" (not "Quick Question About Your Project")

Frequently Asked Questions

What is the difference between sentence case and title case?

Sentence case capitalizes only the first word and proper nouns ("How to write better code"), while title case capitalizes most words ("How to Write Better Code"). Sentence case reads like natural prose. Title case emphasizes importance and formality. Most modern UI guidelines prefer sentence case for interface elements, while title case remains common in article headlines and book titles.

Should I use sentence case for headlines?

It depends on your publication's style guide and brand voice. Sentence case headlines feel more conversational and approachable — common in tech blogs and SaaS products. Title case headlines feel more authoritative and traditional — standard in news publications and academic journals. Many sites use title case for the main title and sentence case for all subheadings, which provides visual hierarchy without formality overload.

Do proper nouns stay capitalized in sentence case?

Yes, always. Proper nouns retain their standard capitalization regardless of case style. "Configure your AWS credentials", "Connect to the GitHub API", "Deploy on Vercel" — brand names, product names, and place names stay capitalized. Acronyms like API, URL, HTML, and CSS also keep their conventional uppercase styling in sentence case.

How do I convert text to sentence case?

Use FlipMyCase to paste any text and convert it to sentence case with one click. The tool handles bulk conversion across multiple lines, making it practical for migrating an entire site's headings. For programmatic conversion, most languages lack a built-in sentence case method, but you can lowercase the string and then capitalize the first character. The tricky part is preserving proper nouns, which requires either a dictionary or manual review.

Conclusion

Sentence case is the modern default for digital writing. It reads naturally, scans quickly, and aligns with design guidelines from Google, Apple, and Microsoft. The rules are simple: capitalize the first word and proper nouns, lowercase everything else.

Convert between sentence case, title case, and other styles instantly at FlipMyCase.