Analyse any text to find its reading age using Flesch-Kincaid, SMOG, or Gunning Fog
This calculator provides an estimate of text readability. Actual reading comprehension depends on many factors including vocabulary, background knowledge, and reading experience.
Reading age is a measure of how difficult a piece of text is to read, expressed as the age at which an average reader could comfortably understand it. In the UK, reading age is widely used by teachers, publishers, and parents to match children with appropriately challenging books and learning materials. This calculator analyses any text you paste in and estimates its reading age using one of three established readability formulas: Flesch-Kincaid, SMOG, or Gunning Fog. Each formula examines sentence length and word complexity (measured by syllable count) to produce a grade level, which is then converted to a UK reading age and Year group equivalent. Understanding the reading age of texts is particularly valuable for primary school teachers selecting classroom resources, parents choosing books for home reading, and content creators writing for specific audiences. The National Literacy Trust recommends that children read texts at their chronological reading age for independent reading, and slightly above for guided or shared reading with an adult. The UK National Curriculum sets clear expectations for reading at each Key Stage. By Year 2 (age 6-7), children should be able to read age-appropriate texts fluently. By Year 6 (age 10-11), pupils are expected to read and understand texts with a reading age of approximately 11-12. Secondary school textbooks typically have a reading age of 13-16, while broadsheet newspapers sit at around 15-17.
To check the reading age of any text: 1. Copy and paste a sample of the text you want to analyse into the text box. For the most accurate result, use at least 100 words and include several complete sentences. 2. Select the readability formula you want to use. Flesch-Kincaid is the most widely used in UK schools. SMOG is considered more accurate for health-related and technical texts. Gunning Fog is commonly used in business and journalism. 3. Review the reading age result, which shows the estimated age in years at which a reader could comfortably understand the text. 4. Check the UK Year group equivalent to see which school year the text is appropriate for. 5. Look at the difficulty rating (Easy, Average, Difficult, or Very Difficult) for a quick assessment of accessibility. 6. Use the average sentence length and syllables per word statistics to understand what is driving the difficulty level. Shorter sentences and simpler words produce lower reading ages.
This calculator offers three readability formulas: Flesch-Kincaid Grade Level: gradeLevel = 0.39 x (words per sentence) + 11.8 x (syllables per word) - 15.59. Reading age = grade level + 5. This is the most commonly used formula in UK education and publishing. SMOG (Simple Measure of Gobbledygook): Counts words with 3 or more syllables (polysyllabic words), then applies: SMOG grade = 3 + square root of (polysyllabic words x 30 / number of sentences). Reading age = SMOG grade + 5. SMOG tends to produce slightly higher reading ages and is favoured in healthcare communication. Gunning Fog Index: Counts complex words (3+ syllables), then calculates: Fog index = 0.4 x (words per sentence + 100 x complex words / total words). Reading age = Fog index + 5. Originally designed for business writing. All three formulas produce a grade level that is converted to a reading age by adding 5 (since Year 1 in the UK starts at age 5). Syllables are counted by identifying vowel groups in each word, with adjustments for silent final e.