About the Sentence Case Converter
Zyff's sentence case converter lowercases text and capitalises the first word of each sentence, which is harder than it looks: the work is deciding where a sentence ends. A period after e.g., approx., Dr. or Fig. is not a boundary, and treating it as one produces a capital in the middle of a clause. This runs the same abbreviation table the word and sentence counts use, on Zyff's servers, so the count and the conversion always agree. Acronyms and names like NASA and iPhone are preserved rather than flattened, which is what makes it usable on real text pasted out of a headline or an all-caps email.
How to convert text to sentence case
Paste the text
A headline in title case, a paragraph shouting in capitals, or a whole document. Up to 100,000 characters in one pass.
Leave acronym preservation on
It is preset on here. NASA, HTML, iPhone and macOS come back as typed instead of Nasa, Html, IPhone and MacOS — which is the difference between output you can use and output you have to fix by hand.
Read the sentence count
The result reports how many sentences it found. If that number looks wrong, the text probably contains an abbreviation or a decimal the boundary logic has treated as a full stop, and the output will show it.
Copy the result
Or switch to Title Case or Capitalized Case from the same box if sentence case turns out not to be what the style guide wanted.
What the Sentence Case Converter does
Abbreviations are not sentence ends
e.g., i.e., approx., Dr., Mr., Fig., vs. and their relatives do not trigger a capital on the next word. This is the single most common failure in a naive sentence-case implementation.
Acronyms and names preserved
ALL-CAPS terms and internally capitalised names pass through as typed, so technical prose survives the conversion.
The pronoun I is kept
Lowercasing everything and capitalising sentence starts would leave a bare i mid-sentence. It is restored.
One boundary rule, two consumers
The sentence count and the conversion share the same logic on the server. A readout that disagreed with the output would be worse than no readout.
Line by line
Each line is treated as its own text, so a list of headings comes back with each item in sentence case rather than the whole list read as one sentence.
At a glance
| Capitalised | First word of each sentence, plus preserved acronyms and names |
|---|---|
| Not treated as a sentence end | Common abbreviations — e.g., i.e., approx., Dr., Fig., vs. and similar |
| Acronym preservation | On by default; ignored for text with no lowercase letters at all |
| Text limit | 100,000 characters per conversion, enforced on the server |
| Stats returned | Characters, characters without spaces, words, sentences, lines |
Frequently asked questions
What is sentence case?
Capitalisation where only the first word of each sentence is capitalised, along with proper nouns and acronyms, exactly as ordinary prose is written. It is the house style for headings at most publications and in most design systems, because it reads as language rather than as a label.
How is sentence case different from title case?
Title case capitalises every significant word in a title; sentence case capitalises only the first word plus proper nouns. Compare How to Compress an Image to a Target File Size with How to compress an image to a target file size. Both are correct — they belong to different style guides, and most modern product writing uses the second.
Will it break my acronyms?
Not with preservation on, which is the default here. Terms that are already all capitals or internally capitalised — NASA, HTML, iPhone, macOS — are passed through as typed. Switch it off only when you are deliberately normalising text that arrived entirely in capitals and want everything lowercased first.
Does it handle e.g. and Dr. correctly?
Yes. A period belonging to a known abbreviation does not end a sentence, so the next word is not capitalised. The same table is used to count sentences, which means the count you see and the capitals you get are decided by the same rule rather than by two implementations that drift.
What happens to text that is entirely in capitals?
Acronym preservation is skipped for it, because every word looks like an acronym and preserving them all would mean changing nothing. The text is lowercased and sentence starts are capitalised, which is what someone pasting an all-caps email actually wants.
Can it fix a sentence that starts mid-line?
Each line is treated as its own text, so the first word of every line is capitalised. If your source wraps a single sentence across several lines, use the remove-line-breaks option first to join them, then convert — otherwise every wrapped fragment is read as a new sentence.