Sentence Counter
Count sentences and analyze them — average words per sentence, longest and shortest, and a flag for run-on sentences.
Sentences will appear here as you type, with their word counts. Long sentences are flagged in red.
ToolsSoup's Sentence Counter is a free online tool that counts how many sentences are in your text and analyzes their structure as you type. Beyond a simple count of sentences, it shows the average words per sentence, the longest and shortest sentence, and flags overly long, run-on sentences so you can tighten your writing. A live breakdown lists every sentence with its word count, highlighting the long ones in red. Everything runs in your browser — no uploads, no sign-up, and your text never leaves your device.
What is a sentence counter?
A sentence counter is a tool that detects sentence boundaries in your text and tells you how many sentences you have written. ToolsSoup goes further than a single number: it measures the length of each sentence in words and reports the average words per sentence, the longest and shortest sentence, and how many sentences run too long. Writers, students, editors, and content marketers use it to control sentence length, spot run-on sentences, and improve readability without leaving the browser.
How to count sentences online
Counting sentences with ToolsSoup takes just a few seconds:
- Type directly into the text box or paste text from anywhere.
- Watch the sentence count, word count, average words per sentence, and longest and shortest sentence update live as you edit.
- Scan the sentence breakdown to see the word count beside each sentence, with long sentences highlighted in red, then click Copy stats to grab the full summary.
What makes a sentence too long?
There is no hard rule, but readability research suggests that sentences over roughly 20 to 25 words become harder to follow, and a long run of such sentences signals run-ons that should be split. This tool flags every sentence longer than 25 words as a long sentence and counts how many you have, so you can see at a glance whether your writing is dense. Mixing short and medium sentences keeps an average of around 15 to 20 words per sentence, a comfortable target for most web and business writing.
How are sentences detected and measured?
Sentences are split on ending punctuation — periods, question marks, exclamation marks, and their full-width equivalents — so each run of text that ends in such a mark counts as one sentence, and a trailing fragment without final punctuation still counts as a sentence. Each sentence's length is the number of words it contains, where a word is any run of non-space characters. The average is total words divided by the number of sentences, and the longest and shortest figures come from the per-sentence word counts.
Why use this sentence counter?
- Counts sentences live and analyzes them — average words per sentence plus longest and shortest sentence.
- Flags overly long, run-on sentences so you can split them and improve readability.
- Shows a per-sentence breakdown with each sentence's word count, highlighting long ones in red.
- Runs entirely in your browser — your text is never uploaded to a server.
- 100% free with no ads, sign-up, or usage limits, and the full summary copies in one click.
Frequently asked questions
How do I count the number of sentences in my text?
Paste or type your text into the box and the sentence count appears instantly, alongside the word count, average words per sentence, and your longest and shortest sentence. There is no button to press — the counts update live as you edit.
What counts as a sentence?
Each run of text that ends in a period, question mark, or exclamation mark counts as one sentence, including full-width punctuation used in some languages. A trailing fragment with no final punctuation still counts so you never lose the last sentence.
What is a good average words per sentence?
For most web and business writing, an average of about 15 to 20 words per sentence reads comfortably. Higher averages tend to feel dense, while very low averages can feel choppy, so mixing sentence lengths usually works best.
How does the tool flag long sentences?
Any sentence longer than 25 words is flagged as a long sentence, counted in the Long sentences stat, and highlighted in red in the breakdown. These are often run-on sentences that are easier to read once split into two.
Is my text private?
Absolutely. All counting and analysis happens locally in your browser using JavaScript, so the text you enter is never sent to or stored on any server.