Reading ease and grade level are two different scales
Flesch Reading Ease runs from 0 to 100 and higher is easier. Around 60–70 is plain English — the level most newspapers and government guidance aim for. Below 30 is heavy going even for a specialist reader.
Grade level is the opposite direction: it estimates the years of schooling a reader needs, so lower is easier. The two are computed from the same underlying counts, which is why they always move together and why seeing both is mostly a matter of which scale you find intuitive.
Why six formulas rather than one
Every readability formula is a rough proxy: they count sentence length and word length, and infer difficulty from that. None of them understands the words. They disagree because they weigh those two inputs differently — Coleman-Liau and ARI count characters per word, the Flesch formulas count syllables, and Gunning Fog and SMOG count words of three syllables or more.
Where all six agree, the estimate is solid. Where they scatter, the text is uneven — typically short sentences carrying long technical words, which the character-based formulas punish and the sentence-based ones do not.
What the score cannot see
A formula cannot tell whether the writing makes sense. "Colourless green ideas sleep furiously" scores as very easy and means nothing. Rearranging a paragraph into nonsense will not change its grade level.
Nor does it know your reader. Technical vocabulary is long and raises every score, even when the audience uses those words daily — a paper for cardiologists should say "myocardial infarction". The score is a signal to check, not a target to hit, and writing to hit it produces the choppy prose that readability tools are blamed for.
Which is why the list of specific sentences below the scores is the more useful half of this page. A number tells you something is wrong; a forty-word sentence tells you where.
How syllables are counted
By rule, not by dictionary. English spelling stopped tracking pronunciation centuries ago — "shed" and "shred" are both one syllable, "shredded" is two, and no pattern predicts all three. The rules here agree with a dictionary on roughly nineteen words in twenty, with a list of common exceptions on top.
So a grade level is accurate to about a grade either way. Treating 8.2 and 8.6 as meaningfully different is false precision, and any tool that implies otherwise is overstating what these formulas can do.
Frequently asked questions
What is a good readability score?
For general audiences, Flesch Reading Ease of 60–70 and a grade level around 8 — which is roughly where most newspapers sit. For a technical or academic audience, lower ease is normal and not a problem.
Why do the formulas give different answers?
They weigh sentence length and word length differently. Coleman-Liau and ARI count characters, the Flesch formulas count syllables, and Gunning Fog and SMOG count long words. A wide spread usually means short sentences with long words in them.
How accurate is the syllable count?
Right on roughly nineteen words in twenty. English spelling has no reliable rule, so this is a heuristic with an exception list rather than a dictionary lookup. Expect a grade level to be accurate to about a grade either way.
Should I write to hit a target score?
No. Formulas count length, not sense, and writing to satisfy one produces choppy prose full of short sentences that still say nothing. Use the score to notice a problem and the sentence list to fix it.
How much text do I need?
At least a hundred words and five sentences for the general scores. SMOG is defined for thirty sentences or more; below that its figure is shown with a warning rather than hidden.
Is my writing uploaded?
No. Everything is counted in the page as you type, which matters when the draft is unpublished or confidential.
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