Readability formulas turn "is this easy to read?" — a question that usually starts arguments — into a number. The most widely used of them is the Flesch family: a score that has been grading insurance policies, military manuals, bestsellers, and web pages for the better part of a century. If you've seen Microsoft Word's "readability statistics," a readability checker in a CMS, or the score WordlyCount shows while you type, you've already met it. Here is what the number actually measures, what a good target looks like, and how to move it.
What the score measures
In 1948, the readability researcher Rudolf Flesch published "A New Readability Yardstick" in the Journal of Applied Psychology, proposing a formula built on two observations: hard writing tends to have long sentences, and long words. His Reading Ease score combines exactly those two inputs:
206.835 − 1.015 × (words per sentence) − 84.6 × (syllables per word)
The result lands between 0 and 100, and higher is easier. A passage averaging 15 words per sentence and 1.5 syllables per word scores roughly 65 — solidly in the plain-English zone. The formula knows nothing about grammar, logic, or tone; it is a proxy, not a critic. But a century of validation studies shows the proxy is a good one: sentence length and word length explain most of what makes readers perceive text as hard.
The score bands, decoded
The raw number means little until you attach it to a reading level. Flesch's own classification, still in use today, looks like this:
| Score | Reading level | What it reads like |
|---|---|---|
| 90–100 | 5th grade | Very easy — picture books, greetings, simple marketing |
| 80–90 | 6th grade | Easy — popular fiction, consumer content |
| 70–80 | 7th grade | Fairly easy — magazines, most ads |
| 60–70 | 8th–9th grade | Plain English — the sweet spot for general web content |
| 50–60 | 10th–12th grade | Fairly difficult — trade publications |
| 30–50 | College | Difficult — academic papers, legal briefs |
| 0–30 | Graduate level | Very difficult — law reviews, dense scientific writing |
As a calibration point, this article sits in the 60–70 band, and so do most well-edited news and help-center pages. Insurance policies famously sit in the 0–30 range — which is precisely why so many jurisdictions now require plain-language rewriting.
Flesch Reading Ease vs. Flesch-Kincaid Grade Level
People say "Flesch-Kincaid score" and mean one of two related but different tests, so it's worth separating them. Flesch Reading Ease is Flesch's original 1948 formula: the 0–100 score above. Flesch-Kincaid Grade Level came later, when researcher J. Peter Kincaid and his team adapted Flesch's work for the US Navy in the mid-1970s so technical manuals could be labeled with the schooling needed to understand them. Its formula — 0.39 × (words per sentence) + 11.8 × (syllables per word) − 15.59 — outputs a US school grade instead of a 0–100 score.
The two tests use the same raw ingredients but answer different questions. Reading Ease says "how easy is this on a 0–100 scale?"; Grade Level says "what grade must you have finished to read it?" They move together: our sample passage scored 65 on Reading Ease and about grade 8 on Grade Level — which is why the 60–70 plain-English band and "grades 8–9" describe the same text from two directions. When a tool or style guide cites a number, check which scale it's on before you compare.
What score should you aim for?
For general web content — blog posts, help pages, marketing copy, emails — the answer is 60–70: plain English that the average adult reads comfortably at a glance. That's the band WordlyCount's analyzer guides you toward, and it's also where most successful consumer publishing lives. There are honest exceptions: a statute or clinical protocol should sit lower, because precision beats ease for its expert audience; children's content should sit 80 or higher. If you're writing for the open web, though, text in the 30s is usually not sophistication — it's friction.
One caution: the formula is a diagnostic, not a target to game. Chopping every sentence into five words will inflate the score and wreck the rhythm. Aim for clarity first; the number follows. For a broader tour of the metrics available, see our readability score guide.
How to raise your score (and your clarity)
Because the formula only weighs sentence length and word length, every fix targets one of the two:
- Split long sentences. Anywhere you'd naturally pause for breath, try a period. Average sentence length under about 20 words keeps the score healthy.
- Swap Latinate words for plain ones. "Utilize" becomes use, "commence" becomes start, "facilitate" becomes help. Each swap removes two or three syllables at a stroke.
- One idea per sentence. Subordinate-clause stacking is the main driver of both long sentences and confusion.
- Cut the middleman verbs. "Conduct an analysis of" is six words hiding "analyze." Nominalizations are syllable machines.
- Read it aloud. Where you run out of breath or stumble, the formula has already flagged it — you're just collecting the data by ear.
Watch the score move as you type
The fastest way to internalize these bands is to see your own numbers change in real time. Paste a paragraph into the WordlyCount analyzer and the Flesch Reading Ease score recomputes on every keystroke — shorten one sentence, replace one long word, and watch the score respond. Pair it with the reading-time estimate, which uses the research-backed average reading speed, and you have a complete picture of how your draft actually meets its readers.