What Is Flesch Reading Ease?

How Flesch Reading Ease Works

Flesch Reading Ease turns a passage of prose into a single number by measuring two mechanical traits: how long your sentences are and how many syllables your words carry. Nothing else feeds the score — not vocabulary difficulty, not whether the argument holds together, not whether the facts are right. Two levers move it, and only two.

The logic is that both traits track cognitive load. Long sentences force a reader to hold more clauses in working memory before the thought resolves, and long words tend to be rarer and more abstract. So a text stitched from short sentences and everyday, one- and two-syllable words scores high and reads easy, while one built from stacked subordinate clauses and Latinate polysyllables scores low and reads hard.

Because the calculation is deterministic, the same passage always yields the same score, which is why regulators, editors, and content tools adopted it. It is baked into Microsoft Word, most SEO plugins, and readability checkers. The catch is that a deterministic surface metric can be gamed: you can raise the number without making the writing any clearer, simply by shortening sentences and swapping in shorter words.

The Flesch Reading Ease Formula

The score is computed as:

206.835 − 1.015 × (total words ÷ total sentences) − 84.6 × (total syllables ÷ total words)

The first bracketed term is your average sentence length; the second is your average syllables per word. Each is scaled by its coefficient and subtracted from the constant 206.835. The result usually lands between 0 and 100, though very long sentences packed with polysyllabic words can push it negative.

The output maps to interpretation bands:

• 90–100 — 5th-grade level, “very easy to read”
• 60–70 — 8th-to-9th-grade level, “plain English”
• 30–50 — college level, “difficult to read”
• 0–30 — college-graduate to professional, “very” to “extremely difficult”

Higher is easier. This is the opposite direction from the related Flesch–Kincaid Grade Level score, which rises as text gets harder — the two use the same inputs but are not interchangeable.

Example of Flesch Reading Ease

The most concrete real-world use of the formula is written into law. Florida Statutes § 627.4145 requires consumer insurance policies sold in the state to be readable, and it defines readable in the exact terms of the Flesch formula: a policy form must achieve a minimum score of 45 on the Flesch Reading Ease test to be approved.

The statute spells out the calculation verbatim. It instructs the insurer to count the total words and divide by the total sentences, multiply that by 1.015, count the total syllables and divide by the total words, multiply that by 84.6, and subtract both figures from 206.835. For forms of 10,000 words or fewer the whole document is analyzed; for longer forms, two 200-word samples per page may be used instead. An officer of the insurer must then sign a certification that the policy clears the 45 threshold.

That threshold is deliberately modest. A score of 45 sits in the “difficult, college-level” band — an acknowledgment that legal contracts are inherently dense, and that dragging them merely up to difficult rather than impenetrable was a meaningful consumer win. It shows both the value and the limit of the metric: it can force a floor on surface complexity, but it cannot make an insurance policy pleasant, and it cannot verify that the shortened sentences still say what they should.

Frequently Asked Questions

The Bottom Line

Flesch Reading Ease boils readability down to a single number between 0 and 100 by weighing how long your sentences run and how many syllables your words carry. Higher scores flag text most readers can follow; lower scores flag dense, specialist prose. It is a useful mechanical check on surface complexity, but it says nothing about whether the writing is accurate, complete, or worth reading.