Sentence Case Converter

How to use the sentence case converter

1. Paste or type your text in the box, or press Open file to load a plain-text file. Example fills in a sample to try.
2. Choose the options. Keep acronyms and brand names (NASA, iPhone) is ticked by default. Untick it to lowercase every word that does not start a sentence. Tick Start a new sentence on every line (lists, headings) (off by default) when each line is its own item or heading.
3. Read the result. It updates as you type. Check names of people and places, which the tool cannot recognize (see below).
4. Press Copy or Download .txt. Use as input moves the result into the input box so you can run another tool on it, and Undo brings the previous text back.

The rules the converter follows

The tool reads your text word by word, lowercases each word, and capitalizes the first letter of a word when a new sentence starts. Exactly:

• A sentence ends at a word that ends with ., !, ? or …, also when a closing quote or bracket follows ("go.", brackets.)). Several marks in a row (now!!!) count once. After a ! or ? followed by a closing quote or bracket, a word you typed with a lowercase first letter continues the sentence, so he said "stop!" and left. comes out as He said "stop!" and left. A capitalized word in that position still starts a new sentence.
• These do not end a sentence: single letters with periods such as a.m., p.m. and U.S., and the abbreviations Mr., Mrs., Ms., Dr., Prof., St., vs., etc., e.g. and i.e.. So “the meeting is at 10 a.m. tomorrow.” becomes “The meeting is at 10 a.m. tomorrow.”
• Initials and names after a title are kept when Keep acronyms and brand names is ticked: a capital initial such as J. and a capitalized word right after an initial or after Mr., Mrs., Ms., Dr. or Prof.. “Mr. Smith arrived. J. K. Rowling wrote it.” stays exactly as typed. A name you typed in lowercase stays lowercase (“dear ms. lee” becomes “Dear ms. lee”). In the middle of a sentence the title itself is currently lowercased: “the meeting with Dr. Smith was fine.” becomes “The meeting with dr. Smith was fine.”, so fix the title by hand.
• A blank line starts a new sentence, so each paragraph begins with a capital even without a period. A single line break does not, unless the line before ended with end punctuation or you tick Start a new sentence on every line. With that option, - item one / - item two on two lines becomes - Item one / - Item two.
• “I” is always capitalized, alone and in I’m, I’ve, I’d and I’ll.
• A sentence that starts with a number keeps its next word lowercase: “3 apples were eaten.” stays as it is. A word that starts with a digit is never capitalized, so “3rd place.” stays too.
• Accented letters are handled like any other letter: “émile zola was french.” becomes “Émile zola was french.”
• Spaces, tabs and line breaks are left exactly as they were, and punctuation is never added or removed. A missing space after a period (world.how) is not treated as a sentence break, so add the space first. To tidy doubled spaces, use the extra spaces remover.

Acronyms, brand names and shouted text

With Keep acronyms and brand names ticked, a word is left exactly as written when its letters look deliberate:

A normal capitalized word such as Paris or Monday does not qualify and is lowercased unless it starts a sentence.

Two cases need care. Shouted text: two or more all-caps words in a row count as shouting, not acronyms, when one has five or more letters, or when a stretch not broken by a comma, semicolon or colon has three or more words (or two, one with four or more letters). “the NASA REPORT WAS LONG and dull.” becomes “The nasa report was long and dull.” because NASA sits inside a run of capitals. Short acronyms next to each other stay acronyms: “we accept PDF, DOCX and TXT files.” and “the FBI CIA rivalry.” keep every acronym, but three in a row without commas count as shouting (“the PDF DOCX TXT files.” becomes “The pdf docx txt files.”). Text with no lowercase letters at all is treated the same way: nothing is kept, so “I WORK AT NASA.” becomes “I work at nasa.” Fix those few words afterwards.

A kept word is left as written at the start of a sentence too, so “iOS and macOS updates.” stays exactly as typed. Untick the option and that sentence becomes “Ios and macos updates.”

Worked examples

The last two rows show the limits: the name after Ms. is kept but the title itself is lowercased, and there is no list of names or places, so Paris and Monday have to be fixed by hand. With the option unticked, the fourth row becomes “The report from nasa was clear. The fbi agreed.”

Paragraphs keep their layout:

great news!
we launched today.

more soon.

becomes

Great news!
We launched today.

More soon.

Sentence case for APA references

In APA 7 reference lists, sentence case capitalizes the first word of the title, the first word of a subtitle (after a colon or em dash), proper nouns, and nouns followed by a number or letter (Experiment 2).

The converter does the first part. It does not capitalize after a colon or before a number, so check those words:

For the journal name and the title in the body of the paper, APA uses title case instead; the title case converter has an APA style, and the title vs sentence case guide explains when to use each.

When sentence case helps

• Caps lock accidents. A paragraph typed with caps lock on, or an email subject in all capitals, comes back readable in one step.
• Headlines and buttons. Many sites and apps write headings, menu items and buttons in sentence case. Paste a list of title-case headings, one per line, tick Start a new sentence on every line, and each one is converted.
• Data exports. Product names or survey answers exported in capitals from a database or CRM read better in sentence case. Keep acronyms ticked so SKUs and brand names survive.
• Reference lists. Convert article titles for APA, then fix the word after each colon.

Excel has no sentence case function (PROPER capitalizes every word), so paste a column here instead, or use the case converter to compare all cases at once.

Questions