Free Readability Checker

Paste text and get two industry-standard scores instantly: Flesch Reading Ease, where higher means easier, and Flesch-Kincaid Grade Level, which maps difficulty to US school grades. Both compute in your browser from sentence length and syllable counts — the same formulas Microsoft Word and government plain-language standards rely on.

Scores arrive with interpretation attached, not as bare numbers: a 65 lands in the plain-English band most web content should target (60–70), while a 42 tells you college-educated readers will tolerate the text and everyone else will bounce.

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Scores update live — paste at least a few sentences for reliable numbers

Paste 10+ words and both scores appear instantly.

Transparent math, honest caveats

Many checkers display a score without disclosing how it was made. Here the inputs are visible: average sentence length and syllables-per-word drive everything, so you always know which lever moves the number — split one 40-word sentence in half and both formulas respond immediately.

The caveats ship alongside the scores. Automated syllable counting is heuristic and can stumble on words like "fire" (one spoken syllable, two vowel groups) or "business" (two syllables, three vowel clusters). And a high score certifies ease, not quality — it can't detect a sentence that's short but confusing.

Before

The party of the first part hereby agrees to indemnify and hold harmless the second party from any claims arising pursuant to this agreement.

After

Flesch Reading Ease ≈ 41 — difficult, college level · Flesch-Kincaid Grade ≈ 13 · Simplified to "If something goes wrong, you agree to cover the other side's costs.": FRE ≈ 89, Grade ≈ 4

The same clause, before and after simplification

Methodology — How the Numbers Are Computed

01Text is segmented into sentences and words, then syllables per word are estimated with a vowel-group heuristic — each vowel cluster counts as one syllable, with adjustments for silent e.
02Flesch Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Shorter sentences and fewer syllables per word push the score toward 100.
03Flesch-Kincaid Grade = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59. The output approximates the US school-grade level the text requires.
04Both scores update live as you edit, so you can watch a 34-point paragraph climb past 60 while splitting sentences and swapping out polysyllabic nouns.
05Everything runs locally in your browser — no upload, no account, no queue, and identical results offline.

Who Uses This, and Why

Web content targeting the plain-English band: Bloggers and help-center writers verify drafts land between 60 and 70 on Flesch Reading Ease before publishing to a general audience.
Plain-language compliance: US federal agencies operate under the Plain Writing Act of 2010; programmers and policy staff test documents against grade-level ceilings.
Patient health materials: Health communicators follow AMA and NIH guidance recommending patient-facing text at roughly a 6th-to-8th-grade level — hard to hit by feel alone.
Academic plain-language summaries: Journals increasingly require lay abstracts; researchers check that summaries actually read at lay level rather than just claiming to.
Marketing copy QA: Landing pages and product descriptions convert measurably better when comprehension friction drops; scores catch drift after a rewrite handoff.
Editorial style-guide enforcement: Content teams set a score floor (say, 55+) for published work and check submissions against it mechanically instead of arguing by vibes.

Pro Tips From Heavy Users

Splitting long sentences raises both formulas faster than swapping short words — attack every 30+-word sentence first.
Hunt nominalizations: "provide assistance" becomes "help," cutting syllables and words in a single edit.
Don't game the score with choppy fragments — readability formulas reward them; human readers don't.
Proper nouns and unavoidable technical terms drag scores down unfairly — test the explanatory prose around them, not the terms themselves.
Check section by section: a document-wide average hides the one brutal paragraph buried mid-page, and that paragraph is where readers quit.

Frequently Asked Questions

What do the Flesch Reading Ease bands mean?

90–100 is very easy (around 5th grade, children's books); 80–89 easy; 70–79 fairly easy; 60–69 plain English — the standard range most web writing targets; 50–59 fairly difficult (high school to college); 30–49 difficult (college); 0–30 very difficult (graduate-level academic, legal, scientific prose).

How does Flesch-Kincaid Grade differ from Reading Ease?

Same two inputs, different weights, different scale: Grade = 0.39 × ASL + 11.8 × ASW − 15.59, where ASL is average sentence length and ASW is syllables per word. A score of 8.4 means roughly eighth-to-ninth-grade reading level. The US Navy commissioned it in 1975 for technical manual triage, and it remains a standard in government documentation.

What score should I aim for?

For general web audiences, target Flesch Reading Ease of 60–70 (roughly 8th–9th grade). Patient education materials often aim lower, around 6th–8th grade, per AMA guidance. Match the ceiling to your audience's familiarity with the topic, not to a universal number.

Can the syllable counts be wrong?

Yes. The estimator counts vowel clusters with silent-e adjustments, so irregular words — "fire," "poem," "every" — can be miscounted by one syllable. Errors wash out statistically across a paragraph, which is why scores on texts under ~100 words wobble and single-sentence scores aren't meaningful.

Is a higher score always better?

No. The formulas measure ease, not quality or correctness. Literary fiction earns complexity deliberately; a recipe at 90 and a physics explainer at 45 can both be exactly right. Chasing maximum score produces choppy, condescending prose faster than it produces clarity.

Who created these formulas?

Rudolf Flesch published Reading Ease in 1948; J. Peter Kincaid and collaborators adapted it into the grade-level formula for the US Navy in 1975. Both use only sentence length and syllables per word, which is why they remain computable everywhere from Word to this page.

Go Deeper

GuideHow to Avoid Plagiarism: Habits That Hold UpPrevent plagiarism with habits that last: what counts beyond copy-paste, note-taking systems, correct quoting, citation styles, AI policy nuance, self-checks.