How to use
- Paste the paragraph or paragraphs into the box.
- Press the button to apply sentence case.
- Read through the output for names, places, acronyms and the word "I", which the tool lowercases.
- Capitalize those manually, then copy the corrected text.
- For headings where every word should be capitalized, use Capitalize Words instead.
- Keep a copy of the original if it contained deliberate capitals you may need to restore.
Formula / how it works
The tool applies two steps:
- Lowercase the whole text with toLowerCase(), which handles accented and non-Latin letters.
- Uppercase the first letter of each sentence. A letter is capitalized if it is the first letter of the text, or if it follows a full stop, question mark or exclamation mark plus at least one space. Opening quotes and brackets between the punctuation and the letter are skipped, so 'hi. "yes"' becomes 'Hi. "Yes"'.
As a regular expression: (^|[.!?]\s+)(["'(“‘]*)(\p{L}) with the u flag, and the captured letter is uppercased.
Why a space is required. The punctuation must be followed by whitespace before the next sentence starts. That keeps decimal numbers, version strings and web addresses intact: "version 2.5 is out" stays as written, and "toolsfreehub.com" does not become "toolsfreehub.Com".
What it cannot know. Sentence case only has rules for sentence starts. Everything else ends up lowercase, including:
- Proper nouns: Lahore, Ahmed, Monday, January.
- Acronyms: NASA becomes nasa (or Nasa at the start of a sentence), PKR becomes pkr.
- The pronoun I: "i think" stays lowercase mid-sentence.
- Brands: iPhone becomes iphone.
A grammar checker or a careful read is needed to restore these, which is usually much quicker than retyping a whole paragraph.
Abbreviations can trigger false capitals. Because "e.g. this" contains a full stop followed by a space, the next word is capitalized: "e.g. This". The same happens after "Dr. khan" (correctly capitalized by luck) or "approx. five" (wrongly). Scan for these after converting.
Line breaks. A newline counts as whitespace, so a sentence that starts on a new line after a full stop is capitalized. A line that starts without a preceding full stop, such as the second item of a list, is not. If each line of a list should start with a capital, add full stops or use Capitalize Words.
Languages. Accented Latin letters (é, ü, ñ), Greek and Cyrillic are capitalized. Urdu, Arabic and Hindi text has no case and passes through unchanged; the Urdu full stop "۔" is not recognised as a sentence end.
Sentence case in style guides. Many publications, including GOV.UK and most UX writing guides, prefer sentence case for headings and buttons because it reads faster than title case. The tool can convert a list of headings if each one ends with a full stop, or you can convert them one at a time.
Worked examples
Mixed punctuation and an acronym
Inputs: hello there. NASA launched it! is it "real"? yes.
Paste and convert. Everything is lowercased, then letters after ". ", "! " and "? " are capitalized. NASA becomes Nasa because it starts a sentence after lowercasing.
Result: Hello there. Nasa launched it! Is it "real"? Yes.
Restore NASA by hand.
Decimal number stays intact
Inputs: version 2.5 is out. update now
Paste and convert. The dot in 2.5 is followed by a digit rather than a space, so it is not treated as a sentence end. Only "version" and "update" are capitalized.
Result: Version 2.5 is out. Update now
URLs such as example.com are protected the same way.
Quote after a full stop, accented letter
Inputs: hi. "yes," she said. élan
Paste and convert. After "hi. " the opening quote is skipped and the y is capitalized. After "said. " the accented é is a letter and becomes É.
Result: Hi. "Yes," she said. Élan
Curly quotes and brackets are skipped too.
Use cases
- Fixing text typed with Caps Lock left on.
- Cleaning chat or SMS exports before quoting them.
- Converting shouty supplier descriptions into readable product copy.
- Normalising headings to sentence case for a style guide.
- Preparing subtitles or transcripts that arrived in all caps.
Tips & limitations
- Restore names, places and acronyms after converting.
- Search the output for " i " and capitalize the pronoun.
- Watch for false capitals after e.g., approx. and similar abbreviations.
- Add full stops to list items if each line should start with a capital.
- Keep the original text until you have checked the result.
FAQ
Why did it lowercase names?
The tool lowercases everything first and only knows where sentences begin. It cannot tell Lahore from lahore, so names need manual fixing.
Will it break decimals or URLs?
No. A letter is only capitalized after punctuation followed by a space, so 2.5 and example.com are not affected.
Does it capitalize after a question mark?
Yes, after full stops, question marks and exclamation marks followed by whitespace.
What happens with quotes at the start of a sentence?
Opening quotes and brackets are skipped, and the first letter after them is capitalized.
Why is there a capital after e.g.?
The full stop in e.g. followed by a space looks like a sentence end. Lowercase the word after it manually.
Does it handle the pronoun I?
No. "i" in the middle of a sentence stays lowercase. A quick find-and-replace of " i " with " I " fixes most cases.
Can I use it for headings?
Yes, for sentence-case headings. Paste one heading at a time, or end each with a full stop.
Runs entirely in your browser; your text is not uploaded. Counts and scores are heuristics, so review the output before you publish it.