Readability Checker

A readability checker measures how easy your writing is to read and shows you what to change. Our free tool gives you a Flesch Reading Ease score, a Flesch-Kincaid Grade Level and an approximate UK reading age, along with your average sentence length and average syllables per word. It then highlights very long sentences, possible passive voice, adverbs ending in -ly and complex words of three or more syllables, with plain-English suggestions for each. Everything runs in your browser, so your copy is never uploaded or stored.

How to use the Readability checker

1. 1 Paste your textCopy the body text of your page, email or document into the box. Leave out menus, footers and cookie banners, as they skew the scores.
2. 2 Read the scoresCheck the Flesch Reading Ease score, the grade level and the approximate UK reading age. For a general audience, aim for a reading ease of 60 or more.
3. 3 Review the highlightsLook at sentences over 25 words, possible passive voice, -ly adverbs and complex words. Each type is highlighted in its own colour.
4. 4 Edit the worst sentences firstSplit long sentences, swap long words for shorter ones and make the doer of the action the subject. Small changes to the longest sentences usually move the score most.
5. 5 Re-check and use judgementPaste the revised text back in. Stop when the copy reads clearly out loud, rather than chasing a perfect number.

How the Flesch scores are calculated

Both Flesch formulas use only two ingredients: how many words there are per sentence, and how many syllables there are per word. Flesch Reading Ease produces a score that usually falls between 0 and 100, where higher means easier. Flesch-Kincaid Grade Level uses the same ingredients weighted differently to produce a US school grade, so a result of 8 means text a typical American eighth-grader could follow.

Because the US grade system starts about five years after birth, we add five to the grade to give an approximate UK reading age. A grade of 8 therefore suggests a reading age of about 13. Treat this as a rough guide rather than an exact measure, since the formulas were developed for American English and count syllables by rule, which is never perfect.

What the scores mean in practice

Scores are most useful for comparing drafts of the same text and for spotting pages that have drifted into heavy, formal language. As a general guide for Flesch Reading Ease:

• 70 and above: easy to read. Suits most consumer websites, service pages and marketing emails.
• 60 to 70: plain English. A sensible target for most small business web pages and public information.
• 50 to 60: fairly difficult. Acceptable for specialist B2B audiences, but worth simplifying where you can.
• 30 to 50: difficult. Typical of reports, policies and legal or technical writing.
• Below 30: very difficult. Reads like an academic paper, and most visitors will struggle on a phone.

Long sentences, passive voice, adverbs and complex words

Sentences over 25 words are highlighted because they are where readers most often lose the thread. GOV.UK's style guidance, for example, recommends keeping sentences to around 25 words. Split them at natural joins such as and, but, which and because, or turn a list buried in a sentence into bullet points.

Possible passive voice is flagged where a form of to be is followed by a past participle, as in the form was submitted by the customer. Active voice, the customer submitted the form, is usually shorter and clearer about who does what. Detection is approximate, so some highlights will be fine as they are, and passive voice is sometimes the right choice, for example when the doer is unknown or unimportant.

Adverbs ending in -ly, such as really, extremely and basically, often add little. Complex words of three or more syllables are not wrong, but each one makes text a little harder. Swap them where a shorter word does the same job: use instead of utilise, help instead of facilitate, start instead of commence. Keep technical terms your audience expects, such as insurance or accountancy, rather than replacing them with vague alternatives.

Readability and SEO

Google does not use a Flesch score or any readability formula as a ranking factor, and no tool can tell you that a particular score will help you rank. What clear writing does is help people find the answer they came for, understand your offer and take the next step, whether that is calling, booking or buying. Those are the outcomes that matter for a business website.

Plain writing also tends to suit search features that quote short passages, such as featured snippets and AI-generated answers, because a clear, self-contained sentence is easier to lift out and understand. That is a reason to write clearly, not a guarantee of being quoted.

A practical approach is to write the first draft for yourself, then edit for the reader. Start each section with the answer or the main point, follow it with the detail, and use headings that say what the section covers. Short paragraphs of two to four sentences are easier to scan on a phone, and bullet points work well for steps, features and lists of options.

Writing for UK audiences and accessibility

Many adults in the UK find dense written information hard going, and almost everyone skims on a phone. Writing in plain English helps people with dyslexia, people reading in a second language, people who are tired or in a hurry, and people using screen readers. It is also part of making public sector and many commercial websites more accessible.

Public bodies in the UK, including GOV.UK and the NHS, publish style guides that favour short sentences, common words and active voice. They are free to read and are a good model for any business that wants its website to be easy to use, even if you keep a warmer, more personal tone.

The limits of readability formulas

A formula cannot tell whether your writing makes sense, is accurate or answers the reader's question. Short words in short sentences can still be confusing, and a nonsense paragraph can score well. Formulas also struggle with lists, headings, product codes, URLs and names, which can push scores up or down unfairly.

Use the score as a smoke alarm, not a judge. If a service page scores 25, it is worth a look. If it scores 62 and reads clearly out loud, it is fine. The best test is still to ask someone from your target audience to read it and tell you what they think the page is offering.

Reading your copy aloud is another quick check that no formula can replace. If you run out of breath before the end of a sentence, it is too long. If you stumble over a phrase, a reader will too. Words with capital letters, such as people's names and place names like Wolverhampton, are not counted as complex words, so local names will not drag your score down unfairly.

Examples you can copy

Before (38 words, passive, complex):
All installations are carried out by our fully qualified and experienced engineers, who will endeavour to ensure that any disruption to your property is minimised and that the work is completed in a timely and efficient manner.

After (21 words, active, plain):
Our qualified engineers fit every boiler. We keep mess to a minimum and finish the job as quickly as we can.

Flesch Reading Ease  = 206.835 - 1.015 x (words / sentences) - 84.6 x (syllables / words)
Flesch-Kincaid Grade = 0.39 x (words / sentences) + 11.8 x (syllables / words) - 15.59
Approx. UK reading age = grade + 5

Common mistakes to avoid

Frequently asked questions