Readability - how to test how easy a text is to read

SMOG (simplified measure of gobbledygook) is a formula that gives a readability level for written material. Readability is an attempt to match the reading level of written material to the "reading with understanding" level of the reader.

The easiest way to establish the readability level of a text is to use the SMOG calculator below developed by Harry McLaughlin PH.D. For further information see www.harrymclaughlin.com/SMOG.htm

For an alternative but less accurate method, see below.

All the readability tests rely on a very rough gauge of the level of reading vocabulary people can expect to acquire by a certain point in their development - they stop generally around the 20 mark. But successful reading is about far more than word recognition - it's about style, content, physical presentation, complexity of intellectual engagement required, learner interest, confidence and skill. Advice on presentation of text

Relating SMOG levels to adult literacy levels

There are no simple answers about relating readability levels to adult literacy levels - they don't equate exactly and are not meant to. SMOG is a measure of readability and not the reading age of a text. The formula was developed to help librarians categorise their stock more easily for learners and practitioners and to act as an indication of level of difficulty, but the adult literacy standards were designed to indicate what specific skills functioned at particular levels, unrelated to age.

It would be impossible to produce materials that solely met the standard definitions at each level. As a rough indication, SMOG 9-10 = Entry Level 3, 11-12 = Level 1 and 13-14 = Level 2 but that it's far from an exact science and SMOG should only be taken as one indicator among many for the suitability of a text. Equating SMOG levels with reading ages is too simplistic. Adult literacy levels - what do they mean?

Calculating the SMOG level of a text

1. Select a page of a book

2. Count 10 sentences

3. Count the number of words which have three or more syllables

4. Multiply this by 3

5. Circle the number closest to your answer

7. Find the square root of the number you circled

8. Add 8 = Readability level

Most people will understand a readability level under about 10.

Family Reading Matters magazine