How to Calculate Readability Levels

A work's readability level indicates how easy it is for people to comprehend.

A work's readability level refers to how easily people can understand it. Two common indicators are the Flesch-Kincaid grade level (which measures approximate grade level) and the Fog Index (which measures the years of education a reader should have to understand the work). Whenever you write about a new or difficult topic, try to keep your writing simple (and thereby your readability at a lower level). Doing this keeps your language concise and clear and helps you convey the information better.

Instructions

Flesch-Kincaid Level

1. Choose a section of your work to test. Pick a paragraph or two.

2. Count the number of sentences, words and syllables. Write down each number so that you don't forget them. Divide the number of words by the number of sentences; this calculates your average sentence length (ASL). Divide the number of syllables by the number of words to calculate the average syllables per word (ASW).

3. Calculate the Flesch-Kincaid grade level using the following formula: (.39 multiplied by ASL) plus (11.8 multiplied by ASW) subtracted by 15.59. The Flesch-Kincaid level gives you a reading level according to school grades. For instance, a 6.2 means that the average sixth grader could read the material.

Fog Index

1. Choose a section of your work that is 100 to 125 words long.

2. Count each individual clause as one sentence and tally them. Count the words. Divide the word count by the sentence count to calculate the average sentence length.

3. Count all words with three or more syllables. Do not include compound words (such as underwater), three-syllable words that start a sentence or proper names. Divide this number by the total number of words. This calculates the percentage of hard words.

4. Add the average sentence length (from Step 2) to the percentage of hard words (from Step 3). Multiply by .4 to calculate the Fog Index level. This readability level measures the approximate years of education a reader should have to understand your work.

References

• Writers Helper: Readability - Beyond the Basics
• Readability Formulas: The Flesch Grade Level Readability Formula
• Using English: Fog Index Definition