Sentence Case Converter

There is no convert button. The tool works as you type, so the result is ready the moment your text is in the box.

1. Type or paste your text into the Input box. The Paste button reads from your clipboard and Clear empties the box.
2. Read the result in the box labelled Sentence case text. It refreshes on every keystroke, even for long documents.
3. Scan the output for names, places and acronyms. These come out in lowercase because the tool has no way of recognising them.
4. Press Copy to put the text on your clipboard, Download .txt to save it as a file, or Use as input to move the result back into the Input box for more editing.

As a worked example, the input tHIS IS a SAMPLE. second SENTENCE here. becomes This is a sample. Second sentence here. A small line under the Input box shows the word, character and line count of what you pasted. The conversion happens in your browser, so private drafts and unpublished notes are safe to use.

The conversion has two stages. First every letter is lowercased, which removes caps lock damage and random capitals. Then four kinds of letter are capitalised again:

• the first letter of the whole text, ignoring any leading spaces;
• the first letter after a full stop, question mark or exclamation mark that is followed by whitespace;
• the first letter on every new line, so each line of a list or a poem starts with a capital;
• the word i when it stands alone, which becomes I.

The second row shows why the whitespace rule matters: the full stop inside 5.30 has no space after it, so it is not mistaken for the end of a sentence. Only Latin letters get capitals, including accented ones such as é and ñ. Greek and Cyrillic text is lowercased but not capitalised afterwards.

Sentence case is a mechanical rule, so a few things need a quick proofread before you use the text.

• Proper nouns and acronyms. PLEASE READ THE NASA REPORT. IT IS IN LONDON. becomes Please read the nasa report. It is in london. Restore NASA and London by hand.
• Abbreviations with a full stop. A full stop followed by a space looks like a sentence end, so e.g. this turns into E.g. This and i.e. into I.e.
• Quotation marks and brackets. In i said "go home." then i left. the result is I said "go home." then I left. The word then stays lowercase because a closing quotation mark sits between the full stop and the space. A sentence that begins with a quotation mark or bracket is also left alone.
• Missing spaces. Two sentences joined as end.Start are treated as one.
• Hard-wrapped lines. Every new line gets a capital, so text copied from a PDF with a line break in the middle of each sentence gains capitals mid-sentence. Join the lines first with the remove line breaks tool.

Fixing these by hand takes seconds, which is still far quicker than retyping a page of text.

Sentence case is the default for paragraphs, emails, captions and subtitles. Many online style guides now ask for it in headings and interface labels too, because it reads calmly and is easy to scan. It is also the quickest repair for text that arrived in capitals, such as scanned and OCR documents, old transcripts, a shouted draft or a spreadsheet cell typed with caps lock on.

If you want the headline style instead, use the title case converter. For plain lowercase there is the lower case converter, and once the text is finished the readability score checker shows how easy it is to read.