What is a good readability score? Flesch scores explained

Readability scores turn a piece of writing into a number that estimates how hard it is to read. They are quick, they are easy to compare, and they are widely used by writers, councils, charities and businesses who want to be understood. But they are crude tools, and a high or low score does not by itself make a text good or bad. This guide explains how the best-known formulas work, with the calculation done by hand on a small example, sets out what a good score is for different readers, shows how to improve a text, and explains where the scores mislead.

By Valtrinity. Updated 18 October 2026.

What readability scores measure

Most readability formulas look at two things: how long the sentences are and how long the words are. Long sentences make readers hold more in their heads at once, and long words, which usually have more syllables, tend to be less familiar. The formulas combine these two measures into a single score.

They do not understand the meaning of the text. They cannot tell whether the writing is clear, accurate, well organised or relevant. A text of short sentences that does not make sense can score well, and a carefully argued text with specialist terms can score badly even if the intended readers find it easy.

Used sensibly, they are a quick check, like spell check: they flag the parts that deserve a second look.

The Flesch Reading Ease formula

The Flesch Reading Ease score is 206.835 minus 1.015 times the average sentence length, minus 84.6 times the average number of syllables per word. Higher scores mean easier text. The average sentence length is the number of words divided by the number of sentences, and the syllables per word is the number of syllables divided by the number of words.

Try a small example: 'The meeting is on Monday. Please bring your laptop. We will start at nine.' That is 14 words in 3 sentences, with 17 syllables. The average sentence length is 14 divided by 3, which is 4.67. The syllables per word is 17 divided by 14, which is 1.21. The score is 206.835 minus 1.015 times 4.67 minus 84.6 times 1.21, which is 206.835 minus 4.74 minus 102.73, giving 99.4.

That is at the top of the scale, which fits: it is very short sentences made of very common words.

The grade level formula

The Flesch-Kincaid grade level uses the same two measures, with the formula 0.39 times the average sentence length plus 11.8 times the syllables per word, minus 15.59. The result is meant to match the years of schooling needed to follow the text in the US school system.

For the same example, that is 0.39 times 4.67 plus 11.8 times 1.21 minus 15.59, which is 1.82 plus 14.33 minus 15.59, giving a grade of 0.56. In other words, the text is easy enough for a very young reader.

To compare with UK school years, add 1 to the US grade, as a rough guide: a US grade 6 is about Year 7 in England. This is only an approximation, and the scales do not match exactly. Treat the grade as a relative indicator, not a measure of any child's reading age.

How to read the scores

The usual bands for Flesch Reading Ease are: 90 to 100, very easy; 80 to 90, easy; 70 to 80, fairly easy; 60 to 70, plain English; 50 to 60, fairly difficult; 30 to 50, difficult; and below 30, very difficult. A grade level of 8 or below suits a wide audience.

A 100-word passage with 8 sentences and 140 syllables has an average sentence length of 12.5 words and 1.4 syllables per word. The Flesch score is 206.835 minus 12.69 minus 118.44, which is 75.7, and the grade level is 4.88 plus 16.52 minus 15.59, which is 5.8. That is fairly easy and suits most adult readers.

Change the numbers to 4 sentences and 170 syllables and the same 100 words score 37.6, which is difficult and corresponds to a grade of 14.2. Fewer, longer sentences and longer words made the same word count much harder.

What is a good score for your readers?

There is no single right target. For general public information, such as a council page, a charity leaflet or a business website, a score of 60 to 70 or higher is a sensible aim. Many organisations that write public services guidance aim for the plainest style they can, because readers may be stressed, in a hurry, reading in a second language or using a phone.

For specialist readers, such as lawyers or engineers, a score in the 30 to 50 range is normal and often unavoidable, because the subject needs technical words. Even then, short sentences help. Experts are also people with limited time.

As a rule, choose your readers first, then choose the score. Check a few pieces of writing that your audience already finds easy and use their scores as a benchmark.

How to make a text easier

Shorten sentences. Aim for an average of about 15 to 20 words, with an occasional long one balanced by a short one. Split a sentence at 'and', 'but' or 'which' if it carries two ideas.

Swap long words for plain ones where the meaning is the same: use 'use' for 'utilise', 'start' for 'commence', 'help' for 'assist', and 'about' for 'approximately'. Keep the technical word when it is the one your readers know, and explain it once.

Use active verbs. 'We will send you the form' is shorter and clearer than 'The form will be sent to you by us'. Put the most important point first, use lists for steps, and keep paragraphs short. These changes help readers even where they do not change the score.

Limits and pitfalls

Software counts syllables with rules, and it gets some words wrong, especially names, numbers and abbreviations. Headings and lists without full stops can be treated as one very long sentence, which pulls the score down. Check how the tool treats these, and test a clean sample of body text.

The formulas were designed for English prose and work poorly for tables, code, poetry and other languages. They also say nothing about layout, which matters a great deal: headings, white space and contrast help readers more than a few points of score.

The danger of chasing a number is that you make the text worse. Cutting every sentence short can make writing choppy and lose the connections between ideas. Use the score to find problem passages and your own judgement to fix them. The best test is to ask a real reader to try the text.

Tools mentioned in this guide

Frequently asked questions