Average Sentence Length Checker
Measure sentence length with this free average sentence length checker. Get Flesch, Flesch-Kincaid, Gunning Fog, and ARI scores plus long sentences.
Sentence Length Analyzer
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What is Average sentence length checker?
Sentence Length Analyzer — Measure sentence length with this free average sentence length checker. Get Flesch, Flesch-Kincaid, Gunning Fog, and ARI scores plus long sentences.
All four scores use the standard published formulas, computed deterministically from your text: Flesch Reading Ease = 206.835 − 1.015·(words/sentences) − 84.6·(syllables/words); Flesch-Kincaid grade = 0.39·(words/sentences) + 11.8·(syllables/words) − 15.59; Gunning Fog = 0.4·(words/sentences + 100·complex/words); ARI = 4.71·(characters/words) + 0.5·(words/sentences) − 21.43. Syllables are counted with a deterministic vowel-group heuristic (silent-e rule, minimum 1); Gunning Fog is simplified (no proper-noun exclusion). "Long" means over 25 words — an editorial threshold.
Why use this average sentence length checker?
Built for average sentence length checker
Measure sentence length with this free average sentence length checker. Get Flesch, Flesch-Kincaid, Gunning Fog, and ARI scores plus long sentences.
Transparent & honest
Syllable counting uses a deterministic vowel-group heuristic (approximation); scores can differ slightly from tools using dictionary-based syllable counts.
Private by design
Everything runs in your browser. Your inputs never leave your device.
Works everywhere
Fully responsive — perfect on desktop, tablet, and mobile. No app needed.
Regularly updated
Regularly maintained and reviewed to ensure accuracy.
Free forever
No accounts, no limits, no watermarks. Use Sentence Length Analyzer as much as you need.
How to use Sentence Length Analyzer
- 1Paste the text you want to analyze — an article, essay, or any passage.
- 2Run the tool to get average sentence length plus four standard readability scores.
- 3Open the long-sentences table to find every sentence over 25 words.
- 4Break flagged sentences in two and re-run to watch the scores move.
- 5Compare drafts: shorter, varied sentences generally score easier to read.
What can you do with Sentence Length Analyzer?
- Long sentence finder — Measure sentence length with this free average sentence length checker.
- Sentence variety checker — Measure sentence length with this free average sentence length checker.
Good to know
- Syllable counting uses a deterministic vowel-group heuristic (approximation); scores can differ slightly from tools using dictionary-based syllable counts.
- Gunning Fog is simplified: words with 3+ syllables count as complex with no proper-noun exclusion.
- "Long sentence" (over 25 words) is an editorial threshold, not a published standard.
- Readability scores describe the text only — they say nothing about search rankings.
How it works
All four scores use the standard published formulas, computed deterministically from your text: Flesch Reading Ease = 206.835 − 1.015·(words/sentences) − 84.6·(syllables/words); Flesch-Kincaid grade = 0.39·(words/sentences) + 11.8·(syllables/words) − 15.59; Gunning Fog = 0.4·(words/sentences + 100·complex/words); ARI = 4.71·(characters/words) + 0.5·(words/sentences) − 21.43. Syllables are counted with a deterministic vowel-group heuristic (silent-e rule, minimum 1); Gunning Fog is simplified (no proper-noun exclusion). "Long" means over 25 words — an editorial threshold.
Examples
Very short sentences — expect a high Reading Ease and low grade levels.
One long, heavy sentence — expect low Reading Ease and high grade levels, flagged in the long-sentences table.
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Frequently asked questions
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