Calculating reading age

What determines the reading age of a text? Sentence length? Frequency of shorter words? The mathematics involved in determining a reading age can lead to an interesting Core Maths classroom discussion.

The Core Maths Reading age resource also asks students to use three of the most used methods to calculating reading age:


Flesch reading test

R = 206.835 - 84.6S -1.015W

where S is the average number of syllables per word and W is the average number of words in a sentence


Forecast formula 

R = 25 - N/10     

where N is the number of one-syllable words in a passage of 150 words.


FOG index                            

R = 0.4(A/n +100l/A)

where A is the number of words in a passage, n the number of sentences in the passage and L the number of words containing three or more syllables (excluding those ending in ‘ing’ or ‘ed’).


Can your students estimate the reading age for a given text? Could they design their own formula or scoring system to determine reading age?

Our complete collection of Core Maths resources can be found here:

Core Maths


Age16-19, FE/HE
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