What are Lexile Measures?

Lexile Reading Measures


The Lexile Framework for Reading is a scientific, standardised method of reading measurement. The Lexile Framework is unique in that it uses a common scale for measuring both the complexity of the text and the reading level of the pupil. The science behind the Lexile Framework is backed by over 30 years of research and technical evaluation; and the Framework is universally applicable across multiple populations (including the UK, the USA and other populations for whom English is a first or additional language).


The Lexile Framework reports a Lexile text measure for a book or piece of text and a Lexile reader measure for a pupil. Having both the Lexile measure of the text and the Lexile measure of the pupil allows educators, parents, and pupils themselves to match an appropriate text with the pupil's level and educational need. Using a precise measurement system helps to eliminate the guesswork associated with selecting a text for a particular pupil. The Lexile Framework provides a level of specificity and guidance previously unavailable. 


Not only do established companies across the assessment, publishing, and EdTech industries use Lexile measures, but the metric is also used extensively by many departments of education, universities and educational institutions across the globe. 


Globe Reader Books
Over 35 million students from 180 countries receive Lexile reader measures... ...from over 65 reading programmes and assessments Over 100 million books, articles and websites have been Lexile text measured.



Lexile measures are represented as a number with an ‘L’ immediately following (for example, 320L). The lower the number, the simpler and easier the text; the higher the number, the more complex and challenging the text. 

It is also possible for a reader to have a Lexile measure to represent their level of reading; when both text and reader Lexiles are used together they provide a powerful tool for informing text choice and ensuring progress. This information sheet is primarily focused on text complexity. 

The Lexile measure for the reading books in Reading Planet is calculated using four main criteria:

Decoding demand Based on the decoding demand of words taking into consideration vowel and consonant patterns in words and the number or syllables within each word – monosyllabic words generating a lower score than multisyllabic ones.
Semantic demand Takes into account factors such as the usual age of acquisition of words, word frequency in English texts and abstractness to evaluate the challenge of word meanings. 
Syntactic demand Measures the sentence length or the complexity of sentences and the relation between each them.
Structural demand Registers the density of text, diversity of phrases and the degree of letter, word and phrase repetition within and across sentences.

Unlike the grading that is provided by book bands, Lexiles are computer-generated measures of readability based on standardised, quantitative data. They arise from scientific evidence-based collections of data over many years.  Book banding is based on human judgement of criteria such as: letter-sound relationships, language structures, text structure, layout, the use of illustrations, and the interests of the child. Book banding may vary between publishers based on interpretations, but Lexile measures relate to one common scale and will not vary. Lexile measures and book bands together, better guide the teacher and learner to find the right reading demand for progress.  


Lexile measures can be used as a complement to book banding and personal judgement to assist you in selecting the most appropriate books for pupils to read, whether independently or for guided reading. For example, if a child is reading independently and fairly securely around Yellow book band, you may want to stretch them a bit further by choosing their next book within the higher Lexile range (401-500L). Or if a guided reading group is just starting out on Purple book band, you might want to go for books within that band with a lower Lexile measure within that band (501-600L).

In Reading Planet Online we have reported Lexile measures in ranges that correlate approximately with Reading Planet book banding in the following way:

Lexile range Approximate correlation with Reading Planet book bands
0-100 Lexile Lilac, Pink A
101-200 Lexile Pink A, Pink B
201-300 Lexile Red A, Red B
301-400 Lexile Red B, Yellow
401-500 Lexile Yellow, Blue
501-600 Lexile Blue, Green, Orange, Turquoise
601-700 Lexile Purple, Gold, White
700-800 Lexile White

Please note that the above is a ‘best fit’ correlation that most books in Reading Planet fall into, but there will always be the occasional title that has a Lexile measure outside these parameters. Non-fiction titles, for example, with a high level of topic-specific vocabulary (the meaning of which may be supported through illustrations or explanations within the text) may measure higher in terms of Lexile than its book band colour would indicate. It is therefore important for teachers to use their own judgement on aspects such as interest level and learners’ prior knowledge alongside book banding and Lexile measures to choose the right books for their pupils. No one tool can ever replace a teacher’s knowledge and understanding of pupils and age appropriateness– and nor should it try, but additional trusted tools certainly can support and save time. 

To find out more about Lexile measures visit: www.lexile.co.uk 

View the Reading Planet Lexile Grid here

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