What Is a Readability Score, and Should You Chase One?
A readability score estimates how hard a piece of writing is to read. The Readability Score Checker gives the Flesch Reading Ease figure and a grade level, and it is worth knowing exactly what it is measuring.
What it actually counts
Flesch Reading Ease uses two inputs: average sentence length and average syllables per word. Nothing else.
The output runs from 0 to 100, where higher is easier. Roughly: 90 and above is very easy, 60 to 70 is plain English, 30 to 50 is difficult, and under 30 is academic. A related formula converts the same inputs into a US school grade level.
So the score is a proxy. Long sentences full of long words are usually harder to read, and the formula detects that reliably. It is a measurement of two surface features, not of clarity.
What it misses
Jargon of the right length. "The lease will be novated" scores well because the words are short. "Novated" is the problem and the formula cannot see it.
Structure. A thousand words in one block scores identically to the same words in eight paragraphs with headings, and one of those is far easier to read.
Whether it makes sense. A grammatically correct sentence that says nothing scores as well as one that says something. The formula has no view on meaning at all.
Being gamed trivially. Chop every sentence in half and the score rises while the writing gets worse - a staccato rhythm is tiring to read. This is the main risk of treating the number as a target.
It is not a ranking factor
Google does not use a readability score, and has not said otherwise. What it does care about is whether people found the page useful, and clear writing helps with that indirectly - which is a real benefit and not the same as a scored input.
So the honest use is as a smoke alarm rather than a target. A score of 25 on a page meant for the general public says something is wrong and worth looking at. A score of 55 against a target of 60 says nothing worth acting on.
What to do when the score is low
Look at the longest sentences first, because sentence length is half the formula and the easier half to fix. A sentence over about 30 words usually contains two sentences.
Then look at the long words that could be short ones - "utilise" for "use", "prior to" for "before". Keep the long words that are genuinely the right word.
Then stop. The remaining gains come from structure and examples, which no formula measures. The Reading Time Estimator tells you something more useful about a long page than another point of Flesch does.
Common questions
What score should I aim for?
Around 60 to 70 for general audiences, lower for technical readers who expect technical language.
Why do technical pages score badly?
Multi-syllable terms. If the terms are correct, a low score is the right answer.
Are there other formulas?
Several - Gunning Fog, SMOG, Coleman-Liau. They use similar inputs and broadly agree.
Does short always mean clear?
No. Short sentences that assume knowledge the reader lacks are not clear at all.
Curious how a page scores?