Sentence counter

Where a sentence ends

A sentence ends at . ! ? or an ellipsis, when what follows is a space or the end of the text — and at a line break, whether or not there was punctuation. The interesting part is everything we deliberately refuse to break on:

• Titles and abbreviations. Dr., Mr., Prof., St., Mt., e.g., etc., Inc. and their relatives never terminate a sentence.
• Initials. J. R. R. Tolkien is one name inside one sentence, not three sentence endings.
• Decimals and version numbers. 3.14 and v2.1 are left intact.
• Semicolons. A semicolon joins clauses rather than ending a sentence, so we do not split on it.

The line break rule deserves the most attention, because it is where we most often disagree with word processors. A slide deck, a set of bullet points or a poem has no full stops at all in many lines. Treating the whole thing as one enormous sentence gives you an average sentence length of ninety words and a readability score that says the text is unreadable, which is not useful information about a slide deck.

Why average sentence length is worth watching

Sentence count on its own is rarely the goal. What people actually want from it is the words per sentence figure in the panel above, because it is the single cheapest diagnostic in editing. Long averages usually mean one of three specific problems rather than a general fault:

• Stacked subordinate clauses. The sentence explains itself three times before reaching its verb.
• Lists smuggled into prose. Four items joined by commas and an and, where a bulleted list would be read in a third of the time.
• Hedging. Each qualification is reasonable; six of them in one sentence is a sentence nobody can hold in their head.

The fix is almost never to shorten every sentence. Uniformly short sentences read as staccato and slightly hostile. What you are aiming for is range: a thirty-word sentence is fine, and it lands much better after a six-word one. Look at the average, then read the paragraph out loud and see where you run out of breath.

Sentence counts in practice

A few places the raw sentence count is the number you actually want:

• Summaries with a stated length. "Describe the incident in no more than five sentences" is a real constraint on a lot of forms.
• Language teaching. Exercises are frequently specified in sentences rather than words, because a sentence is the unit being practised.
• Readability formulas. Flesch Reading Ease and Flesch–Kincaid both take words per sentence as one of two inputs, so an inaccurate sentence count corrupts the score directly. Our guide to readability scores shows how much a single missed boundary moves the number.
• Translation quotes. Some agencies estimate by sentence rather than by word for subtitling and UI strings.

There is more on how to use these figures together in sentence and paragraph length.

Common questions