Sentence Counter
Count sentences instantly as you type, with live average length, a distribution chart and a sentence-by-sentence breakdown. Pro Mode adds Flesch-Kincaid readability scoring, syllable tracking, transition-word analysis and CSV export.
Visual preview only — shows how your text will look once pasted. Copy buttons copy your plain text to the clipboard, ready to paste directly into either app.
Click any sentence in highlight view to jump to it in the list above.
For engaging writing aim for an average of 15–20 words per sentence. Mix short punchy sentences with longer ones. A rhythm of long–short–medium creates pace and emphasis.
CSV lists every sentence with its word, character and syllable count. The offline app is a self-contained file — save it and open anytime, no internet required after the first load.
Sentence Counter — Free Online Tool with Readability Scoring
A sentence counter tells you exactly how many sentences are in a piece of text, along with the average sentence length that shapes how easy it is to read. This one updates live as you type, runs entirely in your browser, and never uploads your text to a server.
Simple period-counting breaks on real writing — "Dr. Smith arrived at 3.14pm" isn't three sentences, and most basic tools get it wrong. This sentence counter checks for common abbreviations, initials, and decimal numbers before treating a period as a sentence boundary, which keeps the count accurate on essays, articles, and reports rather than just clean textbook examples. Beyond the raw count, it tracks average sentence length live, flags a sentence length checker-style distribution across short, medium, long and very-long sentences, and — in Pro Mode — adds full Flesch-Kincaid readability scoring, syllable tracking, and a transition-word analyzer built for academic essays.
1Simple vs Pro — What Each Mode Includes
| Feature | Simple Mode | Pro Mode (Free) |
|---|---|---|
| Live sentence, word & paragraph count | ✓ | ✓ |
| Average sentence length & reading-grade estimate | ✓ | ✓ |
| Sentence-by-sentence breakdown & length distribution | ✓ | ✓ |
| Highlight mode & Google Docs/Word paste preview | ✓ | ✓ |
| Case conversion & text cleanup tools | ✓ | ✓ |
| Flesch-Kincaid readability score | — | ✓ |
| Syllable count & averages | — | ✓ |
| Transition-word & counter-argument analyzer | — | ✓ |
| CSV export & offline app download | — | ✓ |
2Common Reasons People Count Sentences
Teachers use sentence counts to assess writing complexity and development; editors use them to check pacing; content writers use them to avoid walls of text that push readers away. Grammarly's own guidance on sentence counting makes a similar point: tracking sentence structure helps writers maintain clarity, especially in marketing, academic, or professional writing where flow matters. Search engines also reward content that's easy to read — shorter, clearer sentences tend to correlate with better Flesch Reading Ease scores, which several SEO tools track as part of a broader content-quality signal.
3Sentence Length Guide
| Length | Word Range | Effect on Reading |
|---|---|---|
| Short | 1-10 words | Punchy, easy to scan — overuse can feel choppy |
| Medium | 11-20 words | The sweet spot for most general-audience writing |
| Long | 21-30 words | Fine occasionally for building an idea, harder to follow in sequence |
| Very long | 30+ words | Often signals a run-on sentence that would read better split in two |
The distribution across these four bands matters more than any single sentence's length. A whole paragraph of medium-length sentences reads as flat and mechanical, while a mix — a short sentence for emphasis, a longer one to build an idea, then something brief again — creates the rhythm that keeps a reader moving through the page.
4Understanding Flesch-Kincaid Readability
Flesch-Kincaid Grade Level was developed for the U.S. Navy in 1975 to assess the difficulty of technical manuals, and it's still one of the most widely used readability formulas today. It converts two measurable factors — average sentence length and average syllables per word — into a U.S. school grade level: a score of 8 means the text should be understandable by an eighth grader. General-audience writing, including most web content, is usually aimed at roughly grade 7-9; technical or academic writing naturally scores higher, which isn't necessarily a problem as long as it matches the intended reader.
Every count, readability score, and Pro feature — including syllable tracking, transition analysis, and CSV export — runs entirely in your browser using JavaScript. Nothing you type is ever sent to a server.
5Frequently Asked Questions
Grounded in the original readability research — Flesch-Kincaid figures follow the formula from Rudolf Flesch and J. Peter Kincaid's original 1975 work for the U.S. Navy, with additional background from Wikipedia's summary of the Flesch-Kincaid readability tests.
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