Readability Metrics: Are They Getting Your Message?

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What is “readability” and why does it matter? According to the encyclopedia, “Readability is a measure of the accessibility of a piece of writing, indicating how wide an audience it will reach. Readability is a judgment of how easy a text is to understand.” [Wikipedia 2006]

Why is it important? Well, of all the fuzzy uncertainties about whether your marketing message or website text is just right to do the job, one thing you can be certain of is whether your readers can understand it. Your copywriting ability may be good, bad, or indifferent, but you can be absolutely sure that if they can’t read it you don’t have a chance.

Tools of the Trade

While copywriting itself is as much art as science, fortunately readability metrics are easy to calculate, simple to interpret, and tell no lies. Most of us don’t use them but we should. This is the bare minimum — how many of your readers can “get” what you are writing. The tools to determine this are readily accessible, free, and easy to use.

Under Tools in Word, their spell check will calculate some summary counts and averages as well as two readability metrics if you tick off “Check Readability Statistics” in the Options for Spelling and Grammar. But it does this last so you have to go through the whole spell check first. Maybe that isn’t such a bad idea, though…

However, much more powerful is an excellent free tool from This online resource computes readability scores for Word files and whole Web sites in a flash. As they say: “By comparing the readability score of different documents (or Web pages) you can better hone your writing and make sure that you aren’t creating overly complex sentences and paragraphs for your audience.”

Specifically, the tool provides all the following readability and associated metrics:

  • Readability Indexes
  • Sentence Information
  • Word Usage Info
  • Sentence Beginnings

Another free tool that isn’t nearly as powerful but is certainly useful (and you probably haven’t heard of before) is Future Now’s online We-We Calculator. No, it isn’t a urine test for illegal drugs! This nifty tool analyzes the words on your site to see if you are talking mostly about your customers and their needs or if you talking mostly about yourself.

We are rather proud of our businesses, products, and services. But naturally customers don’t much care about that (strange, isn’t it?). Rather, they are very interested in themselves and their own wants and needs. Future Now’s quick analysis can help you adjust that balance. You will probably be surprised by the objective analysis.

Readability Scores

This is a good time to review the various popular readability indexes, all of which are calculated by the tool. Some take a different approach or measure things a bit differently and, in any case, everyone selects just a few favorites that they rely on regularly. Here they are:

The Automated Readability Index (ARI) is designed to gauge the understandability of a text. Like many of the other indexes, its output is an approximate representation of the U.S. grade level needed to comprehend the text. Unlike the other indices, the ARI, along with the Coleman-Liau, relies on a factor of characters per word, instead of the usual syllables per word. Formula:

The Coleman-Liau Index was designed to gauge the understandability of a text. Like the ARI but unlike most of the other indexes, Coleman-Liau relies on characters instead of syllables per word. Although opinion varies on its accuracy as compared to the syllable/word and complex word indices, characters are more readily and accurately counted by computer programs than are syllables. Formula:

The Flesch-Kincaid Readability Tests are designed to indicate how difficult a reading passage is to understand. There are two tests, the Flesch Reading Ease Index and the Flesch-Kincaid Grade Level Score. These are supposedly the same measures, just placed into a different scale but the results of the two tests do not always correlate closely. Formula:

The Gunning-Fog Index is a test indicating the number of years of formal education that a person requires in order to easily understand a text on the first reading. That is, if a passage has a fog index of 12, it has the reading level of a U.S. high school senior. The test was developed by Robert Gunning, an American businessman, in 1952. Texts that are designed for a wide audience generally require a fog index of less than 12. Formula:

The Laesbarhedsindex (LIX) readability formula is useful because it’s simple can be used on documents of any Western European language. The test calculates an index score of a text sample based on sentence length and number of long words (i.e., words containing seven or more characters). Formula: []

SMOG (Simple Measure Of Gobbledygook) is a widely-used readability formula that estimates the years of education needed to understand a piece of writing. It yields an outstandingly high 0.985 correlation with the grades of readers who had 100% comprehension of test materials. G. Harry McLaughlin invented it in 1969 as a more accurate and more easily calculated substitute for the Gunning-Fog_Index. Formula:

What’s Good?

A “good” score, of course, depends on your target audience, your chosen style (part of branding), and what you mean to do. But there are some general rules of thumb. According to Future Now [2006] referring to various published studies, an “ideal writing standard” might be as follows:

  • No more than 4.25 characters per word.
  • No more than 5% passive voice.
  • No less than an 80% readability.
  • A Flesch-Kincaid Grade Level between 4 and 65 (sky’s the limit, it seems…)
  • A Fog Index higher than 13 puts you in the danger zone.

While the Grade Level seems arbitrary depending on who your target audience is, it should be said that the average best-seller is around Grade 4 level, newspapers about 6, and business books 7-8. Lower than you might have thought.

Of course your audience can read at higher levels — but you want to make your message easy to read. If your readability scores seem wildly out of line with your audience’s abilities, Future Now offers a few strategies for making repairs:

  • Rewrite passive sentences so they become active sentences.
  • Remove unnecessary words like “the” or “a”, extraneous words like “that”, adjectives that don’t pack a meaningful punch or anything that isn’t helping your message.
  • Replace 50-cent words with 5-cent words whenever the difference isn’t critical to your style or meaning.
  • Let your verbs do the work you’d otherwise assign your adjectives.
  • Take the time to learn how your customers talk about your product or service so you can write to them in language they actually use.

Only One Piece of the Puzzle

Obviously this is just a quick introduction to the topic. But taking a closer look at your text content in a quantitative way may provide some surprises as well as pointers to adjustments you may wish to make. While there are sound guidelines, in general, there is no “good” or “bad” score — it all depends on what you want to achieve.

If you are aiming at the widest possible audience then the lowest reasonable grade level is what you want. If it’s a fairly serious discussion for a B2B audience then maybe you don’t want to dumb-down your content but prefer to aim at a grade 8-10 comprehension level. It all depends.

Terms like “Monetizing Behavioral Targeting” or even more complex ones may not please the readability programs but you know you have to use them in certain circumstances. “Metrics” is an awfully useful word, yet it isn’t familiar to most people at first. Sometimes you have to do what you gotta do — don’t throw the baby out with the bathwater.

And, of course, these numbers aren’t the only critical element in your copywriting: “Obviously, numbers alone can’t make you a good writer. Many other factors contribute to readable, comprehensible writing.” We might also add “effective” there.

These factors include not only what good copywriters do, but also elements such as font, size, color, placement, etc. in your presentation or website design. Even what day and time you send out an email marketing message. Lots of pieces to this puzzle and the more you know about each the better your chances of success!


Future Now. “Can Your Customers Read What You Write?” GrokDotCom Volume 139 09/15/06.

“Readability,” Wikipedia 10/03/06.

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