📝 Sentence Case Converter

About the Sentence Case Converter

This sentence case converter runs entirely in your browser. Paste any text into the box above and click Convert to produce sentence-case output where the first letter of each sentence is capitalized and everything else is lowercased. Nothing is uploaded to a server — the conversion happens instantly with JavaScript on your device.

How sentence case works

The tool first lowercases the entire input. It then identifies sentence boundaries by looking for sentence-ending punctuation (., !, ?) followed by whitespace and a letter, and capitalizes the first letter after each boundary. The very first letter of the text is also capitalized.

When to use sentence case

• Body text and prose — The most natural form for paragraphs, articles, and email body text.
• Headings that aren't Title Case — Many publications and style guides use sentence case for section headings.
• Cleaning up ALL CAPS text — Convert text that was typed in caps lock into a readable, properly cased form.
• Standardizing mixed-case input — Normalize text that has inconsistent capitalization into a uniform style.

How to use the converter

1. Paste or type your text in the input box.
2. Click Convert — the sentence-case result appears in the output box.
3. Click Copy to copy the result to your clipboard, or Clear to start over.

Frequently asked questions

Does this tool upload my text? No. All conversion happens locally in your browser. Your text never leaves your device.

Will it preserve proper nouns like "iPhone" or "McDonald"? No. The converter lowercases everything first, so proper nouns with internal capitals will be normalized. This keeps behavior predictable.

How are sentence boundaries detected? The tool looks for ., !, or ? followed by one or more spaces and then a letter. Abbreviations like "Mr." may cause a false sentence break.

Is there a length limit? The only limit is your browser's available memory. Even very long documents convert instantly.