Sentence Counter

Any run of text ending in a full stop, question mark or exclamation mark. That is the same rule almost every counter uses, and it is right for ordinary prose, but it is a rule about punctuation rather than grammar. Two things follow. A sentence joined by a semicolon counts as one, even though it contains two independent clauses. And a sentence with no terminal punctuation — the last line of a draft, a heading, a bullet without a full stop — is still counted, because the counter treats the end of the text as an ending.

Because the full stop in an abbreviation looks identical to the full stop at the end of a sentence. 'Dr. Smith arrived.' counts as two sentences, not one. The same happens with 'e.g.', 'i.e.', 'etc.', initials such as 'J. R. R. Tolkien', and decimals written in text. If your writing is dense with abbreviations, expect the count to run high, and check the average words per sentence — an unexpectedly low average is usually the giveaway that abbreviations are being split.

For general web writing, an average of roughly 15 to 20 words works well, and the Federal Plain Language Guidelines recommend aiming for about 20 as an upper bound. The average matters less than the spread, though. Twenty sentences all of exactly 18 words is monotonous; a mix of six-word sentences and twenty-five-word ones reads faster than the average suggests. Use the average to spot drift and the long-sentence count to find the specific places worth rewriting.

Twenty words is where comprehension starts to fall off measurably for a general audience, and it is the threshold most plain-language guidance uses. It is not a rule — technical, legal and academic writing routinely runs longer for good reasons, and a single long sentence in a paragraph of short ones is a stylistic choice, not a fault. The count is there to tell you how many you have, so that 'my sentences are too long' becomes a specific number you can act on.

Directly, and more than any other factor you control. Average words per sentence is a term in Flesch Reading Ease, Flesch-Kincaid Grade Level, the Gunning Fog Index and the Automated Readability Index. In Flesch Reading Ease each extra word of average sentence length costs roughly one point. That is why splitting one long sentence often moves a grade level more than replacing a dozen long words does.

A bullet ending in a full stop counts as one sentence; a bullet without terminal punctuation is folded into whatever follows it. Headings behave the same way. If you are counting a document that is mostly lists, the sentence count will be lower than the number of items you can see, and the average words per sentence will be misleadingly high. For list-heavy text, the paragraph and word counts describe the structure better than the sentence count does.