Analyse
Readability checker
Six formulas, plus the specific sentences holding your score back — not just a number.
What the score means
Flesch Reading Ease maps text to a 0–100 scale, where higher is easier. It is built from two inputs only: average sentence length and average syllables per word. That simplicity is both its strength and its ceiling — it is stable and reproducible, but it cannot tell whether your argument makes sense.
| Score | Reads as | Audience |
|---|---|---|
| 90–100 | Very easy | 5th grade |
| 80–89 | Easy | 6th grade |
| 70–79 | Fairly easy | 7th grade |
| 60–69 | Plain English | 8th–9th grade |
| 50–59 | Fairly difficult | 10th–12th grade |
| 30–49 | Difficult | College |
| Below 30 | Very difficult | College graduate |
For general web writing, aim for 60 or above. Plain-language guidance in government and healthcare often targets 60–70. Technical documentation for a specialist audience sitting at 40 is not a failure; the audience has the vocabulary.
The six formulas, and where they disagree
All six formulas here are pure arithmetic over sentence length, word length and syllable counts. They were developed for different purposes and will not agree with each other, which is a feature rather than a bug — a wide spread tells you the text is uneven.
- Flesch–Kincaid Grade — the same inputs as Reading Ease, expressed as a US school grade.
- Gunning Fog — weights polysyllabic words heavily. Punishes jargon.
- SMOG — designed for health materials; considered reliable on short passages.
- Coleman–Liau — uses letter counts rather than syllables, so it avoids syllable-estimation error.
- Automated Readability Index — characters per word plus sentence length.
Syllable counting is the weak link. English orthography does not map cleanly to syllables, so every implementation uses heuristics and every implementation is wrong on some words. Coleman–Liau sidesteps this by counting letters, which is why it is worth reading alongside the others rather than in isolation.
Fix sentences, not words
Because sentence length is one of only two inputs, splitting long sentences moves the score more than any amount of synonym substitution. A 45-word sentence broken into three costs you nothing in meaning and can shift Reading Ease by ten points or more.
This is why the panel lists your hardest individual sentences rather than only showing a total. A single 60-word sentence in an otherwise clear page will drag the average down and is invisible in a document-level score. Fix the outliers first, then look at vocabulary.
Passive-voice detection here is a regex heuristic — a form of "to be" followed by something that looks like a past participle. It over-flags. Treat the count as a prompt to reread, not a verdict.
Common questions
What is a good Flesch Reading Ease score?
For general web writing, 60 or above. Plain-language standards in government and healthcare typically target 60 to 70. Technical documentation for specialists often sits in the 40s, which is appropriate for that audience. Below 30 is heavy going for almost anyone.
Why do the formulas give different grade levels?
They were built for different purposes and weight their inputs differently — Gunning Fog punishes polysyllabic words heavily, Coleman-Liau uses letter counts instead of syllables, SMOG was designed for short health passages. A wide spread between them usually means the text is uneven rather than that one formula is wrong.
How accurate is the syllable counting?
It is a heuristic, as it is in every implementation of these formulas. English spelling does not map cleanly to syllables, so some words are miscounted. This affects every readability tool equally. Coleman-Liau avoids the problem by counting letters, which is why it is worth reading alongside the syllable-based scores.
How do I improve my score fastest?
Split your longest sentences. Sentence length is one of only two inputs to Flesch Reading Ease, so breaking a 45-word sentence into three moves the score more than any vocabulary change. The panel lists your hardest sentences for exactly this reason.