Readability science
What is the Flesch reading ease score and how to use it on your blog
Flesch reading ease is the number every other readability score gets compared to. If you have ever seen “ease score 65” in Yoast or Microsoft Word, you have already met it. The score is older than colour television and still does the job better than most modern alternatives. That is why it has outlasted them.
What is the Flesch reading ease score?
Flesch reading ease is a number between 0 and 100 that estimates how easy a piece of writing is to read. Higher scores mean easier reading. A score of 60 to 70 reads like a UK broadsheet news article. A score below 30 reads like an academic paper.
Rudolf Flesch, an Austrian-American writing consultant, published the formula in 1948 in his book The Art of Readable Writing. The US Navy adopted it in the 1970s. Microsoft built it into Word in the 1990s. Yoast SEO surfaces it inside WordPress today. It is the closest thing the readability world has to a universal currency.
What is the Flesch reading ease formula?
The formula is short enough to fit on a Post-it note.
206.835 minus (1.015 times average words per sentence) minus (84.6 times average syllables per word)
In English: take the average number of words in each sentence. Take the average number of syllables in each word. Plug both numbers into the formula and you have a score between 0 and (very rarely) 121.
That is the entire intelligence behind the score. It does not look at vocabulary or grammar or meaning or whether the writing makes any sense. It only looks at two structural signals: sentence length and word length.
What is a good Flesch reading ease score?
The answer depends on who you are writing for. The table below is the standard interpretation mapped to UK audiences.
| Score | Reads like | Audience |
|---|---|---|
| 90 to 100 | Very easy | Year 5 (age 9 to 10) |
| 80 to 90 | Easy | Year 6 (age 10 to 11) |
| 70 to 80 | Fairly easy | Year 7 (age 11 to 12). NHS plain English target. |
| 60 to 70 | Standard | UK broadsheet news. Good for most blogs. |
| 50 to 60 | Fairly difficult | Quality magazine writing. |
| 30 to 50 | Difficult | University essays. |
| 0 to 30 | Very difficult | Academic and scientific papers. |
For a public-facing blog or marketing site, 60 to 70 is the realistic sweet spot. Lower than that and you will lose readers. Higher than that and the writing starts to feel patronising for an adult audience.
Why is my Flesch score so low?
Almost always one of two reasons. Long sentences or long words. Sometimes both.
Sentence length is the bigger lever. Every extra word in an average sentence drops the score by about one point. Every extra syllable in an average word drops it by about 85 points. The formula is brutal here, which is why a single technical word in a short sentence will barely move the score but a paragraph full of them will tank it.
The patterns that crush sentence length are easy to spot once you know what you are looking for.
- Compound sentences joined by “and” or “but” or “, which” that link two complete thoughts
- Lists that should have been bullet points
- Subordinate clauses that interrupt the main sentence (“the Flesch score, which was developed in 1948 by Rudolf Flesch, who worked as a consultant for the US Navy, measures sentence length”)
- Adverbial throat-clearing at the start of every sentence (“In this case, we can see that…”)
Fix sentence length first. Then look at word length. Most “complex” English words have a Saxon-rooted short alternative. “Utilise” becomes “use”. “Approximately” becomes “about”. “Commence” becomes “start”. “Facilitate” becomes “help”. Strike them out as you edit.
What Flesch reading ease will not tell you
Flesch is good at what it does and dangerous outside its lane. A short sentence about fiscal multipliers can score 80 and still completely confuse a reader who has never heard of fiscal multipliers. “Bovine” and “horse” score the same number of syllables but only one of them belongs in a vet textbook. Subheads and bullets and bold key terms all change how a reader experiences an article but none of them touch the score. Boring writing scores fine. Engagement is a separate metric and Flesch was never built to measure it.
How to actually push a Flesch score up
Editing for Flesch is not about dumbing down. It is about removing friction. Three moves cover most of the work.
Move one: split your sentences at “and”. Most “and” connectors are joining two ideas that should be standalone sentences. Splitting them keeps the meaning and lifts the score.
Move two: cut the throat-clearing. “It is important to note that”, “It should be remembered that” and “What is interesting here is that” are all syllables that say nothing. Delete them.
Move three: leave the jargon in and help the reader. If the technical term is the right word, do not replace it with three vague ones. Keep it. Then give the reader a way out. WP AI Explainer is built for this exact moment. The reader hits a word they do not know, taps it, sees a one-sentence explanation and reads on. The Flesch score does not change. The completion rate does.
Does Flesch reading ease work for UK English?
Yes. Flesch counts syllables and words and English syllable structure is the same on both sides of the Atlantic. UK spellings such as “colour” and “realise” score identically to “color” and “realize” because both have the same syllable counts. The score does not care which spelling you use.
The benchmarks shift slightly though. UK newspapers tend to write at a higher reading ease score than US equivalents. UK tabloid scores often land in the high 70s. US tabloids land in the low 70s. If you are calibrating against UK norms, treat 65 as a comfortable target for general-audience writing.
How to check the Flesch score of your WordPress posts
You have three good options on a WordPress site.
Yoast SEO shows a per-post Flesch reading ease score in the right-hand sidebar under “Readability analysis”. It is free. It lives inside the post editor. It updates as you type.
Readable.com or Hemingway give you a second opinion outside Yoast. Paste your draft in for a fresh score and a sentence-by-sentence highlight of the hard bits.
Microsoft Word will give you Flesch reading ease and Flesch-Kincaid grade level if you tick the readability statistics box in File > Options > Proofing. Useful if you draft offline before pasting into WordPress.
None of these will help the reader once the post is live. For that, install WP AI Explainer from the WordPress plugin directory. Readers can tap any hard word for an instant plain-English explanation, which is what Flesch was always trying to measure a proxy for.
Frequently asked questions
What is the Flesch reading ease formula?
206.835 minus (1.015 times the average number of words per sentence) minus (84.6 times the average number of syllables per word). Higher scores mean easier reading.
What is a good Flesch reading ease score?
For a public-facing website, 60 to 70 is a sensible target. That puts the writing at roughly UK reading age 13 to 15. Government and healthcare guidance should aim for 70 or higher.
Why is my Flesch score so low?
Almost always because sentences are too long or words have too many syllables. Split sentences at every “and” or “but” that joins two complete thoughts. Replace polysyllabic words (“utilise” becomes “use”). The score will climb fast.
Does Flesch reading ease work for UK English?
Yes. The formula counts syllables and words and does not care which spelling you use. UK and US English score the same as long as the sentence structure is similar.
Want this on your own site?
WP AI Explainer turns confusing words into instant tooltips on every WordPress post. Free on wordpress.org, with a pro option for sites that need bulk scanning.