Sentence Counter

What this tool measures

Sentence length is one of the few writing metrics that reliably predicts how hard a text feels. A page of 40-word sentences is heavy going even when every word is simple. This tool counts your sentences, measures each one, and points at the ones doing too much work.

It reports the total, the average, the longest and shortest sentence, and a full table so you can see the rhythm of the piece rather than a single summary number.

How to use it

1. Paste your text. The table fills in immediately.
2. Set the flag threshold to whatever your house style expects — 20 for plain-language public writing, 25 for general prose, 35 for academic work.
3. Switch the list order to Longest first to bring the problem sentences to the top.
4. Turn on List only the flagged sentences when you are editing a long document and want a working list.
5. Copy or download the report to share the findings with a co-author.

How sentences are detected

English has no reliable single rule for where a sentence ends, so this tool uses a heuristic that handles the common traps.

• A sentence closes at ., !, ? or … when the next non-space character begins something new — a capital letter, a digit, or an opening quote or bracket.
• Runs of punctuation stay together, so Really?! is one ending, not two.
• A closing quote or bracket after the punctuation stays with the sentence it belongs to.
• Known abbreviations do not end a sentence: titles such as Mr. and Prof., business forms such as Inc. and Ltd., months, weekdays, e.g. and i.e., and single initials such as the J. in J. Smith.
• Decimal numbers are protected, so a 3.5 percent rise stays in one sentence.
• A blank line always closes the current sentence, which keeps headings and list items from merging into the paragraph below.

Word counts per sentence use the same rule as the rest of the site: split on whitespace, count anything containing a letter or digit.

Two limits are worth knowing. An abbreviation that is not on the list — an obscure journal citation style, for example — will split a sentence in two. And a sentence that ends without punctuation, as headings often do, merges with what follows unless a blank line separates them.

Examples

Consider this text:

Prof. Reed published the study in Sept. 2025.
It found a 2.4 percent difference. Was that meaningful? Probably not.

The tool reports 4 sentences. The periods in Prof., Sept. and 2.4 are all recognized as something other than sentence endings.

Now a length example. This 41-word sentence would be flagged at the default threshold:

Although the committee had already reviewed the proposal twice, and although several members had raised the same objection on both occasions, the chair decided to defer the vote once more, which frustrated almost everyone in the room that afternoon.

Split at the comma before the chair decided and you get two sentences of 22 and 19 words, both comfortably inside the threshold, with no change to the meaning.

Who uses it

• Editors checking that a draft meets a plain-language standard before publication.
• Students breaking up the long sentences that creep into a first draft at 2am.
• Technical writers keeping instructions to one action per sentence.
• Speech writers testing whether a line can be delivered in one breath.
• Translators checking that a long source sentence became a readable target sentence.
• Anyone learning English who wants feedback on sentence rhythm without a subscription.

Privacy and security

Sentence detection runs entirely in your browser. The manuscript, report or client draft you paste is never transmitted, stored or logged, and it disappears from memory when you close the tab.

Only your threshold and sort preferences are saved locally, so the tool opens configured the way you like. The privacy policy describes exactly what is kept.