Measuring Reading Difficulty

A number of different formulas are available for testing the difficulty of written materials. These formulas estimate grade levels by analyzing the complexity of the writing; specifically, they look at words per sentence, syllables per word, the percentage of big words in the text, the number of unfamiliar words, and similar factors that influence comprehensibility.

Common formulas for assessing the complexity of print materials include:

• The Fry formula.
• SMOG (Statistical Measure of Gobbledygook).
• Flesch tests (Flesch-Kincaid and Flesch Reading Ease).

You can do these tests by hand or by computer. Many common software programs include readability tests: both WordPerfect® and Microsoft® Word®, for example, offer the Flesch-Kincaid tests. However, while computer-based tests can be quick, they are not as reliable as testing done by hand, nor are they as useful for identifying the reasons why the text may be difficult. Also, to conduct an accurate test on a computer, you have to prepare your document carefully, so the time savings may be negligible.

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