Readability Metrics: Are They Getting Your Message?

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

Because it is important? Well, out of all the confusing uncertainties about whether your marketing message or website copy is the right one to get the job done, one thing you can be sure of is whether your readers can understand it. Your writing skills can be good, bad, or indifferent, but you can be absolutely certain that if they can’t read you, you don’t stand a chance.

tools of the trade

While copywriting itself is as much an art as it is a science, luckily readability metrics are easy to calculate, simple to interpret, and they don’t lie. Most of us don’t use them, but we should. This is the minimum: how many of your readers can “get” what you are writing. Tools to determine this are readily available, free, and easy to use.

In Tools in Word, your spell checker will calculate some summary counts and averages, as well as two readability metrics if you check “Check readability statistics” in Spelling and Grammar Options. But it does the latter, so you have to go through all the spell checking first. Although maybe not such a bad idea…

Much more powerful, however, is an excellent free tool from This online resource calculates readability scores for Word files and entire websites in the blink of an eye. As they say, “By comparing the readability score of different documents (or web pages), you can better hone your writing and make sure you’re not creating sentences and paragraphs that are too complex for your audience.”

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

  • Readability indices
  • prize information
  • Word Usage Information
  • Prize starts

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

We are quite proud of our businesses, products and services. But of course customers don’t care much about that (strange, isn’t it?). Rather, they are very interested in themselves and their own wants and needs. Future Now’s quick scan 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 indices, all of which are calculated by the tool. Some take a different approach or measure things a little differently, and in any case, everyone selects just a few favorites that they regularly trust. Are here:

Tea Automated Readability Index (ARI) is designed to measure the comprehensibility of a text. Like many of the other indices, its output is a rough representation of the US grade level needed to understand the text. Unlike the other indices, the ARI, along with the Coleman-Liau, is based on a factor of characters per word, rather than the usual syllables per word. Formula:

Tea Coleman–Liau index was designed to measure the comprehensibility of a text. Like the ARI but unlike most other indices, the Coleman-Liau is based on characters rather than syllables per word. Although opinion varies on its accuracy compared to syllable/word and complex word indices, computer programs count characters more easily and accurately than syllables. Formula:

Tea Flesch-Kincaid readability tests they are designed to indicate how difficult it is to understand a reading passage. There are two tests, the Flesch Reading Ease Index and the Flesch-Kincaid Grade Level Score. These are supposedly the same measures, just placed on a different scale, but the results of the two tests don’t always correlate closely. Formula:

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

Tea laesbarhedsindex The readability formula (LIX) is useful because it is simple and can be used in documents of any Western European language. The test calculates an index score for a text sample based on the length of the sentence and the number of long words (namely, 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 produces an extraordinarily high correlation of 0.985 with the scores of readers who comprehended 100% of the exam materials. G. Harry McLaughlin invented it in 1969 as a more precise and easier to calculate substitute for the Gunning-Fog_Index. Formula:

What is good?

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

  • No more than 4.25 characters per word.
  • No more than 5% passive voice.
  • No less than 80% readability.
  • A Flesch-Kincaid grade level between 4 and 65 (the sky’s the limit, it seems…)
  • A fog index above 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 bestseller is around grade level 4, newspapers around level 6, and business books 7-8. . Lower than you might have thought.

Of course, your audience can read at higher levels, but you want your message to be easy to read. If your readability scores seem way out of line with your audience’s skills, Future Now offers some strategies for making amends:

  • Rewrite passive sentences so that they become active sentences.
  • Eliminate unnecessary words like “the” or “a,” extraneous words like “it,” adjectives that don’t have significant impact, or anything that doesn’t help your message.
  • Replace 50 cent words with 5 cent words as long as the difference is not critical to your style or meaning.
  • Let your verbs do the work that you would otherwise assign to your adjectives.
  • Take the time to learn how your customers talk about your product or service so you can write to them in the language they actually use.

Just one piece of the puzzle

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

If you’re targeting the widest possible audience, then the lowest reasonable rating level is what you want. If this is a serious enough discussion for a B2B audience, then you may not want to simplify your content, but rather aim for a grade 8-10 level of understanding. It all depends.

Terms like “Behavioral Targeting Monetization” or even more complex ones may not appeal to readability programs, but you know you should use them in certain circumstances. “Metric” is a terribly useful word, but it’s not familiar to most people at first. Sometimes you have to do what you have to do: don’t throw the baby out with the bath water.

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

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


Future Now. “Can your customers read what you write?” GrokDotCom Volume 139 09/15/06.

“readability,” Wikipedia 03/10/06.

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