Flesch Reading Ease calculator — score 0 to 100
Calculate Flesch Reading Ease for any text. The classic 1948 formula scores text on a 0–100 scale where higher means easier. Paste text below and see your score plus interpretation.
- Outputs 0 (very confusing) to 100 (very easy)
- Standard interpretation table for every score range
- Formula breakdown and worked example
- Free, no signup, runs in your browser
The formula
206.835 − 1.015 × (words / sentences) − 84.6 × (syllables / words)Three inputs: total words, total sentences, total syllables. Long sentences hurt the score. Long words hurt the score. That’s the whole math.
Score interpretation
- 90–100:Very easy. 5th grade. Short, simple sentences. Children’s books, basic instructional text.
- 80–90: Easy. 6th grade. Short sentences with familiar words. Many bestselling novels.
- 70–80: Fairly easy. 7th grade. Plain English. Most marketing copy targets this range.
- 60–70: Standard. 8th–9th grade. Major newspapers (NYT, WSJ). The sweet spot for most professional writing.
- 50–60: Fairly difficult. 10th–12th grade. Technical writing for educated audiences.
- 30–50: Difficult. College. Academic and specialist writing.
- 0–30: Very confusing. Graduate / professional. Legal documents, scientific papers.
A worked example
Take the sentence: “The dog ran fast.”
- Words: 4
- Sentences: 1
- Syllables: 4 (the=1, dog=1, ran=1, fast=1)
Score = 206.835 − 1.015 × (4/1) − 84.6 × (4/4) = 206.835 − 4.06 − 84.6 = 118.18
That’s above 100 — the formula isn’t capped, but scores rarely exceed 110 for natural text. Now consider: “The phenomenon of comprehensive readability assessment demonstrates significant methodological implications.”
- Words: 10
- Sentences: 1
- Syllables: ~24
Score = 206.835 − 1.015 × 10 − 84.6 × 2.4 = 206.835 − 10.15 − 203.04 = −6.36
The formula goes negative for very dense text. Negative scores are interpreted as “below 0 — extremely difficult.”
When to use Flesch Reading Ease
- Marketing copy— aim for 70+ for accessibility.
- Blog content— 60–75 works for most audiences.
- Email newsletters— 70+ correlates with higher open and click rates.
- Customer support docs— 65+ to minimize support tickets from confused users.
- Onboarding flows— 75+ for activation copy.
Limitations to know
- Doesn’t measure meaning. A grammatical sentence of short words can still be nonsense. Flesch only measures form, not content.
- Punishes long technical words.“Photosynthesis” has 5 syllables but is universally understood. The formula doesn’t distinguish between familiar long words and genuinely complex ones.
- Noise on short passages. Run Flesch on at least 100 words for stable results.
- English-specific. Direct application to other languages gives approximations only.