Readability Score
Checker

What is a readability score?

A readability score is a numerical measure of how easy or difficult a piece of text is to read and understand. These scores are calculated using established linguistic formulas that analyse sentence length, word length, and syllable count. The goal is to give writers an objective measure of their writing's accessibility — going beyond gut feeling to provide concrete data.

The most widely used formula is the Flesch Reading Ease score, developed by Rudolf Flesch in 1948. It produces a number between 0 and 100 — higher scores mean easier reading. The formula considers two key variables: average sentence length and average number of syllables per word. Short sentences with simple words score highest; dense academic prose scores lowest.

Readability formulas were originally developed for the US military and government, who needed to ensure that documents and instructions could be understood by the broadest possible audience. Today they are used across journalism, publishing, education, healthcare, law, and digital marketing.

Flesch Reading Ease score guide

Understanding what your score means in practice helps you calibrate your writing for the right audience. A score of 90–100 is considered very easy — the kind of language used in children's books and simple instructions. Scores of 70–80 are easy reading, comfortable for most adults. Scores of 60–70 represent standard English, suitable for newspapers and general web content. Scores of 50–60 are fairly difficult, typical of quality press and professional writing. Scores of 30–50 are difficult, found in academic and technical writing. Scores below 30 are very difficult — the territory of scientific journals, legal documents, and specialist publications.

Most popular websites and blog posts aim for a score between 60 and 70. Marketing copy often targets 70 or higher. Academic writing typically scores between 20 and 50 depending on the discipline — and that is often entirely appropriate for the audience.

What is the Flesch-Kincaid Grade Level?

The Flesch-Kincaid Grade Level is a companion formula that converts readability into a US school grade equivalent, making it easier to understand in practical terms. A score of 8 means a typical 8th-grader (aged 13–14) could understand the text. A score of 12 suggests college-level writing. A score of 6 means the text is accessible to most adults without difficulty.

Microsoft Word has included Flesch-Kincaid scoring in its spelling and grammar checker since the 1990s, which has made it one of the most widely recognised readability metrics in the world. The US Department of Defence uses it to evaluate the readability of military documents. Many plain English campaigns use it as their primary benchmark.

Most content writers aim for grade 6–8 for general audiences. Healthcare information is often targeted at grade 6 or below to maximise patient comprehension. Legal documents, by contrast, frequently score at grade 16 or higher — which is why many jurisdictions now mandate plain language requirements for consumer contracts.

Readability scores by industry and audience

Different writing contexts call for different readability targets. Understanding the norms for your industry helps you calibrate your writing effectively.

Journalism and news: Broadsheet newspapers like The Times and The Guardian typically score between 50 and 65 on the Flesch scale. Tabloid publications aim higher, often 65–75, using shorter sentences and simpler vocabulary to reach the widest possible audience quickly.

Marketing and advertising: Effective marketing copy typically scores 70 or above. The most memorable advertising slogans — "Just Do It", "Think Different", "Have a Break" — score extremely high because they use the shortest possible words to convey the maximum impact. Digital marketing studies consistently show that higher readability correlates with better conversion rates.

Academic writing: Scholarly articles in humanities disciplines typically score between 30 and 50. Science and medicine often score lower still, sometimes below 20, due to the technical vocabulary required. This is not a problem — the audience has the specialist knowledge to decode it. The issue arises when academic writing style leaks into contexts where it is inappropriate, such as public health communications or school teaching materials.

Educational materials: Teaching materials should be calibrated to the reading level of the students. Materials for primary school children should score 80 or above. Secondary school teaching materials typically target 60–75. University study guides often sit at 50–65. Teachers and educators use readability scores to check that their materials are accessible without being patronising.

Healthcare and patient information: The NHS and most health services recommend that patient-facing information targets a reading age of no more than 11, equivalent to a Flesch score of approximately 70 or above and a grade level of 6 or below. Studies show that even highly educated patients prefer health information written simply and clearly, particularly when anxious or unwell.

How readability affects SEO and content performance

Google does not use readability scores as a direct ranking factor, but readability has a significant indirect effect on search rankings through engagement metrics. Pages with clearer, more readable content tend to have longer average session times, lower bounce rates, and higher return visitor rates — all of which are positive signals that Google uses to assess content quality.

Research by Semrush and other SEO platforms has found that top-ranking content for competitive keywords tends to score between 50 and 70 on the Flesch scale — readable enough for a broad audience without being so simplified that it lacks depth. Very low readability scores (below 30) are associated with higher bounce rates, as readers abandon text they find difficult to follow.

For content marketers, readability optimisation is one of the highest-return improvements available. Rewriting a piece to improve its readability score typically takes less time than other SEO tasks and can meaningfully improve engagement metrics within days of republishing.

How is reading time calculated?

Reading time is estimated at 238 words per minute, which reflects the median adult silent reading speed according to research published in the journal Reading and Writing by Brysbaert (2019), which analysed reading speed data from 190 studies involving nearly 18,000 participants. This is the most comprehensive study of adult reading speeds to date and is the basis for the reading time estimates used by platforms including Medium.

It is worth noting that reading speed varies considerably by individual and by content type. Technical or unfamiliar content is read more slowly than narrative prose. Reading on screen is typically 20–30% slower than reading print. The 238 WPM figure represents a useful average for planning purposes, but individual readers may experience significantly different times depending on their familiarity with the subject matter.