Searching for Readability Through the Fog

Anyone who writes for a living has to be conscious of readability. Or at least anyone who writes for marketing and/or advertising purposes.

Since becoming a professional writer, I’ve taken pride in keeping things readable. Reining in long sentences and paragraphs. Avoiding complex words. Adopting a friendly, conversational tone. After so many years of writing, habits like these become second nature.

When clients review my work, they rarely comment on readability. If anything, they’re more likely to make suggestions that hurt readability. Add in some more detail to this sentence. Throw in some multisyllabic techno-jargon. Etc.

So I was surprised to see that readability actually took precedent with this new technology client of mine. Before delivering website copy, I first had to run it through the Gunning fog index.

This little tool has been around since the 1950s, but it was the first I’d heard of it. The Wikipedia entry explains how the fog index works. To sum up, it gauges the readability of your writing by weighing the average sentence length and percentage of words with three or more syllables.

After digesting your prose, the fog index spits out a figure indicating the number of years of formal education you’d need to easily comprehend the text. Scoring a 12 means a high school graduate could get it.

My client encouraged me to aim for an 11, and I figured it’d be no problem. But it was. My first draft scored a 15.5, so I had to go back and make some fixes. Soon I found myself shortening sentences that I had thought couldn’t be shortened, and replacing the occasional big word with a little one.

Of course, when writing for technology clients, it’s tough to cut out many of those big words (how else can you say “virtualize,” anyway?). Still, it’s worth trying. And even though I’ve always considered my writing to be very readable, it’s good to know how I could do better. So thank you, Gunning fog index. I’ll be seeing you again soon.

By the way, this blog entry scored an 8.6. Sweet.

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6 replies
  1. Michael Flint says:

    Dan – what a cool notion. I’m definitely going to try that tool out. I wholeheartedly agree that if you take the time to re-read what you are typing, you can shorten, simplify, and make it more readable. That’s the whole point, isn’t it. Getting your copy read? (5.753)

  2. Rich Nadworny says:


    You can use the spelling and grammar tool in Word for grammar statistics. If you remember your PR classes in grad school, and before, the golden number is Mark Twain’s 75% reading ease for Huck Finn, which usually translates to a 7th grade reading level.

    Seth Godin had a great piece on this last year. Someone analyzed authors readability stats and found that Seth and Malcolm Gladwell were consistently in the high 60s and low 70s, which accounted for a big part of their popularity.

  3. Anonymous says:

    Such an interesting article. I love your content and explaining very nicely what they want to explain. Thanks for sharing such and interesting article here.

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