Flesch Reading Ease: Formula, Score Chart and Examples

The Flesch Reading Ease score rates how easy English text is to read on a 0 to 100 scale, using only two things: average sentence length and average syllables per word. Higher scores mean easier reading. For most business web pages, a score of 60 to 70 is a sensible target, and many service pages benefit from going higher.

The Flesch Reading Ease formula is:

206.835 − 1.015 × (total words ÷ total sentences) − 84.6 × (total syllables ÷ total words)

That's the short answer. The longer one is more useful, because the score is easy to misread. It can tell you a paragraph is heavy going. It can't tell you whether the paragraph is true, relevant or in the right order. This guide explains how the formula works, what the bands mean, how it relates to the Flesch-Kincaid grade and UK reading ages, and how to raise a score without making your writing worse.

If you want to test a page as you read, paste it into our free readability checker. It calculates the score in your browser, flags long sentences and possible passive voice, and nothing is uploaded.

Key takeaways

Flesch Reading Ease scores text from 0 to 100 using only sentence length and syllables per word, and higher means easier.
Microsoft suggests 60 to 70 for most standard documents, which is a sensible target for UK small business web pages.
GOV.UK guidance makes plain English mandatory and suggests splitting sentences over 25 words, which lifts your score naturally.
A good score does not prove a page is clear, accurate or useful, so treat it as a prompt to edit, not a pass mark.

What the Flesch Reading Ease score measures

Rudolf Flesch published the Reading Ease formula in the late 1940s. It was designed for English prose and looks only at surface features of the text:

Average sentence length (ASL): total words divided by total sentences.
Average syllables per word (ASW): total syllables divided by total words.

Long sentences and long words push the score down. Short sentences and short words push it up. Nothing else counts: not vocabulary difficulty, not jargon, not layout, not whether the text makes sense.

The formula

Microsoft's documentation for Word's readability statistics gives the standard version:

Flesch Reading Ease = 206.835 – (1.015 × ASL) – (84.6 × ASW)

The syllable weight is far larger than the sentence weight. Adding one word to every sentence costs about one point. Raising the average word length by a tenth of a syllable costs about eight and a half points. In practice, swapping long words for short ones moves the score faster than anything else.

A worked example with numbers

Say a 100-word passage has 5 sentences and 150 syllables.

Words per sentence: 100 ÷ 5 = 20
Syllables per word: 150 ÷ 100 = 1.5
Sentence part: 1.015 × 20 = 20.3
Syllable part: 84.6 × 1.5 = 126.9
Score: 206.835 − 20.3 − 126.9 = 59.6

That sits just below the 60 to 70 "plain English" band. Cutting the average to 16 words per sentence (by splitting a couple of long sentences) adds about 4 points. Cutting the syllables to 140, by swapping a handful of long words for short ones, adds about 8.5 points. Do both and the passage scores about 72.

A worked example in words

Take this sentence from a typical service page:

"Our organisation facilitates comprehensive maintenance solutions for commercial heating installations throughout West Yorkshire."

That's one sentence of 14 words with a lot of three- and four-syllable words. It scores very low, well into the "difficult" range.

Now the plain version:

"We service and repair heating systems for businesses across West Yorkshire."

Same meaning, 12 words, mostly one and two syllables. The score jumps dramatically, and the sentence is easier to scan on a phone.

Flesch Reading Ease score bands

Sources differ slightly on where the bands start and stop, but the commonly used interpretation looks like this:

Score	Description	Rough equivalent
90–100	Very easy	Easily understood by an 11-year-old
80–89	Easy	Conversational English
70–79	Fairly easy	Most popular consumer writing
60–69	Plain English	Understood by most 13 to 15-year-olds
50–59	Fairly difficult	Older secondary school level
30–49	Difficult	University level
0–29	Very difficult	Academic and legal writing

Microsoft's guidance is that for most standard files "you want the score to be between 60 and 70." That's a reasonable floor for a small business website. Pages that people use under pressure, such as emergency call-out pages, booking instructions, or anything a customer reads on a mobile in a car park, often deserve 70 or above.

Scores can technically fall below zero or rise above 100 with extreme text. A string of one-syllable words in very short sentences can exceed 100. A single 80-word sentence full of technical terms can go negative.

Flesch-Kincaid grade level and UK reading age

The Flesch-Kincaid Grade Level uses the same two inputs with different weights. It was developed by J. Peter Kincaid and colleagues for the US Navy in a 1975 research report, and Microsoft gives it as:

Flesch-Kincaid Grade = (0.39 × ASL) + (11.8 × ASW) – 15.59

Written out in full, that's 0.39 × (total words ÷ total sentences) + 11.8 × (total syllables ÷ total words) − 15.59. For the 100-word example above, it gives (0.39 × 20) + (11.8 × 1.5) − 15.59 = 7.8 + 17.7 − 15.59 = 9.9, roughly a US tenth-grade level.

The result is a US school grade. A score of 8.0 means a US eighth grader should be able to follow the text. Microsoft recommends around 7.0 to 8.0 for most documents.

Converting a US grade to a UK reading age

US grades don't map neatly onto UK year groups, and there's no official conversion. A widely used rule of thumb is to add about five to the US grade to get an approximate reading age:

Flesch-Kincaid grade	Approximate reading age	Roughly equivalent to
5	10–11	End of primary school
7	12–13	Years 8 to 9
9	14–15	GCSE years
12	17–18	Sixth form
13+	18+	University

Treat these as approximations. A reading age of 12 doesn't mean a page is written for children. It means an adult can read it quickly, without effort, which is exactly what you want when someone is comparing three suppliers on their phone.

What GOV.UK says about readable writing

GOV.UK is the best-known plain English standard in the UK, and its writing guidance is public. A few points from the current clear language guidance are worth borrowing:

"Plain English is mandatory for all of GOV.UK."
"Try to split up sentences that are over 25 words long."
"Do not use formal or long words when easy or short ones will do."
Use the active voice rather than the passive voice.

The guidance also cites National Literacy Trust figures, including that "1 in 6 adults in England have very poor literacy skills." And it points out that specialists aren't the exception: "people with higher levels of literacy prefer plain English." Solicitors, accountants and engineers read your pages too, and they don't want to wade through padding either.

You'll often see a "reading age of 9" quoted as the GOV.UK target. The current guidance pages don't set a numerical reading age. They focus on short sentences, common words and active voice, which are the same habits that raise a Flesch score.

How to improve your Flesch Reading Ease score

Work through these in order. The first two do most of the work.

Split long sentences. Look for "and", "which", "while" and semicolons joining two ideas. Make them two sentences. Our readability checker highlights sentences of 25+ and 35+ words so you can find them quickly.
Swap long words for short ones. "Use" for "utilise", "help" for "facilitate", "buy" for "purchase", "about" for "approximately", "start" for "commence".
Cut nominalisations. "Carry out an assessment of" becomes "assess". "Make a decision" becomes "decide".
Prefer active voice. "We'll call you back within an hour" beats "A callback will be arranged within one hour."
Talk to the reader. "You" and "we" naturally produce shorter, more direct sentences.
Use lists for sequences. A five-step process crammed into one sentence scores badly and reads badly. A numbered list fixes both.
Keep necessary technical terms, but explain them once. If your customers search for "Gas Safe registered" or "SPF record", use those words. Don't replace a term people actually search for just to win points.

What not to do

Chasing the number can damage a page. Common mistakes:

Chopping every sentence into fragments. Text made of three-word sentences scores well but reads like a telegram.
Removing precise words. "Boiler" is two syllables, "heating appliance" is six, but the precise word is also the shorter one here. Sometimes it isn't, and precision should win.
Rewriting quotes, legal wording or regulated statements. Terms and conditions, FCA risk warnings or medical information may need specific wording. Keep the required text and simplify the explanation around it.

Limits of readability formulas

Readability formulas are useful screening tools, not judges of quality. Keep these limits in mind:

They don't understand meaning. Flesch can't tell a clear sentence from a nonsensical one with the same word and syllable counts.
They ignore vocabulary familiarity. "Ague" is short. "Television" is long. Most readers know the second word better.
They ignore structure. Headings, bullet points, tables and white space make a big difference to how easy a page feels. The score doesn't see any of it.
Syllable counting is approximate. Software estimates syllables using rules, so two tools can give slightly different scores for the same text.
They were built for English prose. Scores for other languages, code samples, product specs or lists of place names are unreliable.
They don't measure readers. Your audience matters. A page for IT managers can use terms that a page for first-time landlords shouldn't.

Use the score to find the heavy paragraphs, then read them aloud. If you trip over a sentence, your customers will too.

Does readability affect SEO?

Google doesn't use the Flesch Reading Ease score as a ranking factor, and there's no readability threshold to hit. Readability scores you see in SEO plugins and content tools are those tools' own suggestions, not something Google measures or publishes. What Google does ask is whether content is written for people. Its guide to creating helpful, reliable, people-first content asks whether visitors will leave feeling they've learned enough to achieve their goal.

Readable writing helps with that indirectly. People who understand a page are more likely to stay, contact you or buy. Clear, direct sentences are also easier to quote in search snippets and AI-generated answers. Our guide to getting content into AI Overviews covers that side.

Readability also overlaps with accessibility. Plain language helps people with dyslexia, people reading in a second language and anyone tired or distracted. Our UK website accessibility checklist covers the wider requirements.

A quick readability checklist for a web page

Before you publish a service page, blog post or product description:

Paste it into the readability checker and note the Flesch score.
Fix every sentence flagged as 35+ words, then most of the 25+ ones.
Replace formal words with everyday ones.
Check the opening paragraph answers the reader's question directly.
Break long sequences into numbered steps.
Run the word counter to check average sentence length and the longest sentence.
Read it aloud once.

For longer content, our guide to how long a blog post should be explains why length matters less than answering the question fully. If you're writing in volume, for example dozens of location or product pages, Make It Flow can help you build a review step into your content workflow so drafts get checked before anyone publishes them. Talk to us if that would help.

FAQ

What is a good Flesch Reading Ease score?

For most business web pages, aim for 60 to 70 or higher. Microsoft's guidance says most standard documents should score between 60 and 70. Pages people use quickly, such as booking steps or emergency services, often benefit from scores above 70. Technical or legal content may score lower, which is fine if the audience expects it and the wording is still as plain as possible.

How is Flesch Reading Ease calculated?

The formula is 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). In words: 206.835 minus 1.015 times the average sentence length, minus 84.6 times the average syllables per word. A 100-word passage with 5 sentences and 150 syllables scores 59.6. Because the syllable weight is much larger, using shorter words usually raises the score more than shortening sentences.

What is the difference between Flesch Reading Ease and Flesch-Kincaid?

Both use sentence length and syllables per word. Flesch Reading Ease gives a 0 to 100 score where higher is easier. Flesch-Kincaid Grade Level converts the same inputs into a US school grade, where lower is easier. A Reading Ease score of 60 to 70 roughly lines up with a grade of 8 to 9.

What reading age should a website be written for?

There's no legal standard for private businesses. Many UK organisations aim for a reading age of around 12 to 14 for general audiences, which keeps text quick to scan without sounding childish. GOV.UK's guidance focuses on plain English, common words and sentences under 25 words rather than a fixed age.

Is Flesch Reading Ease a Google ranking factor?

No. Google doesn't use readability formulas as a ranking signal. It does want content that's written for people and helps them achieve their goal. Clear writing supports that, and it can improve how people respond to your page, but raising your Flesch score alone won't change rankings.

Why do different tools give different Flesch scores?

Tools count syllables and sentences in slightly different ways. Some treat headings or list items as sentences, others ignore them. Syllable counting relies on rules that don't handle every English word perfectly. Small differences are normal, so compare scores from the same tool over time rather than across tools.

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