Key takeaways
The Flesch reading ease score rates how easy a piece of English text is to read on a scale that runs roughly from 0 to 100. Higher is easier. It was created by Rudolf Flesch in 1948 and is still built into Microsoft Word, most SEO plugins and our own readability checker. It looks at only two things: how long your sentences are and how long your words are.
Score = 206.835 − 1.015 × (total words ÷ total sentences) − 84.6 × (total syllables ÷ total words)
The first ratio is average sentence length. The second is average syllables per word. Both pull the score down, but syllables have the heavier weight, so long words hurt more than long sentences.
Take a 100-word paragraph with 5 sentences and 140 syllables.
68 sits in the plain English band. Split those 5 sentences into 8 and the average falls to 12.5 words; the score rises to 75.7 without changing a single word.
| Score | Reading level | US school grade | Typical content |
|---|---|---|---|
| 90–100 | Very easy | 5th grade | Children's books |
| 80–90 | Easy | 6th grade | Conversational copy, ads |
| 70–80 | Fairly easy | 7th grade | Consumer blogs, product pages |
| 60–70 | Plain English | 8th–9th grade | Most good web content, news |
| 50–60 | Fairly difficult | 10th–12th grade | B2B articles, reports |
| 30–50 | Difficult | College | Academic writing |
| 10–30 | Very difficult | College graduate | Research papers |
| 0–10 | Extremely difficult | Professional | Legal contracts |
The grade level version uses the same inputs and turns them into a US school grade:
Grade = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59
For the example above: 0.39 × 20 + 11.8 × 1.4 − 15.59 = 8.7, so a reader at about 9th grade can follow it. Plain language guidance for public documents commonly targets grade 8 or below.
Aim for 60 or higher on most pages and 70+ for content aimed at a broad consumer audience. Technical guides can sit in the 50s without problems, as long as terms are explained. A score is a guide, not a target: a page full of short, choppy sentences can score 85 and still be confusing.
Google has said it does not use readability formulas as a ranking signal. Its guidance on helpful content focuses on whether the page serves the reader, and clear writing is part of that. Pair the score with the right length for the topic; our guide to blog post length covers that side.
Flesch counts syllables, not meaning. It cannot tell whether your words are familiar, whether your structure makes sense or whether the reader already knows the topic. Short technical terms like "API" or "ROI" score as easy even when they are not. Use the score to spot problem paragraphs, then read the text aloud. Check length and keyword use at the same time with the word counter.
For most websites, 60 or higher. 60 to 70 is plain English; 70 to 80 is fairly easy and suits consumer content. Academic or legal text often scores below 30.
They use the same two inputs (sentence length and syllables per word) but different weights. Reading ease gives a 0 to 100 score where higher is easier. Grade level gives a US school grade, where lower is easier.
Not directly; Google does not use a Flesch score as a ranking factor. But clear writing helps people stay, understand and act, which is what Google says its systems aim to reward.
Yes. Very long sentences full of long words can go below 0, and very short sentences of one-syllable words can go above 100. The 0 to 100 range covers almost all real text.
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