Gunning Fog Index Calculator
Find out how many years of formal education a reader needs to understand your text. Paste your content below for an instant Fog score.
Breakdown
What Is the Gunning Fog Index?
How it works
Developed by Robert Gunning in 1952, the Fog Index measures the complexity of English writing. It calculates a score based on average sentence length and the percentage of complex words — defined as words with three or more syllables.
Score reference
A score of 6 is easily understood by most people. Scores of 8–12 are suitable for general audiences. Scores of 12–17 require high school to college education. Above 17 is considered extremely difficult and suited only for specialists.
Common benchmarks
Time magazine typically scores around 11. The Wall Street Journal averages 11–12. Academic journals often score 15–20. Most business communication guidelines recommend keeping the Fog Index under 12.
How to Reduce Your Gunning Fog Score
Target complex words
The Fog Index heavily penalizes words with 3+ syllables. Audit your text for unnecessarily complex vocabulary. Often a simpler word exists that conveys the same meaning without losing precision.
Shorten sentences
Long sentences compound the effect of complex words. Breaking long sentences into two shorter ones will lower your Fog score quickly. Aim for an average sentence length below 20 words.
When fog is unavoidable
Technical fields like medicine, law, and engineering require precise terminology that naturally increases the Fog score. In these cases, a higher score is expected and appropriate for the audience.