The Writing Clarity Rating

How would you like an easy way to see how clear your writing is? Whether it be an e-mail message, a report or even a speech you are giving.

The Infogineering Clarity Rating does that – it gives any piece of your text a number, which allows you to see where you can improve how clear you are being.


In the 1980’s, the United States’ Army produced a report that was designed to teach their personnel how to write clearer.

Since the Army (as any large organisation) has various levels of intelligence, people at one level need to make sure they are being clear to another. Using obscure and overly-descriptive terms can mean that other people may not be able to understand what they are saying. In the field of battle, where seconds of confusion can cost lives, it is critical that people understand what they are being asked to do.

One of the major outcomes of this Army report was a simple technique that gives you a Clarity Index for your writing.

This is a simple way of taking any block of text you write (around 200 words) and performing a relatively simple calculation on it. The result is a number… which is your Clarity Index. Generally, the lower the number, the clearer you are being.

The Clarity Index calculation uses a combination of two factors:

  1. The percentage of all words that are longer than three syllables
  2. The average number of words per sentence

In both cases, the target is 15. By adding the two numbers together, you get the Clarity Index. The aim is get to get this number to around 30. Above 40, and your sentences are too long or your words are too complicated. Below 20, and you may be too abrupt.

However, there are also other factors that could be used to make text more clearer. For example, the number of sentences in a paragraph.

Infogineering Clarity Rating

The Infogineering Clarity Rating builds on this Clarity Index and adds the average paragraph length into the equation. This is significant, because our attentions lower after the first couple of sentences in a paragraph – so very long paragraphs tend not to be read.

One other difference is that the Infogineering Clarity Rating defines long words as over 8 characters – unlike the Clarity Index which uses words over 3 syllables. There are two reasons for this.

  • It is faster to count words based on their letter number than their syllable count, as you have to speak the words slowly to do the latter.
  • The English language is constructed in a way that the more frequently used words (such as “the, a, of, we, or, and”) are shorter than less-used words (such as “relentlessly”, “pertinent”, “regarding”). Therefore, a simple way to make your writing more clear is to find a shorter word that does the same thing. For example, rather than saying “approximately five people,” say “about five people.”

The downside of adding paragraph length into our calculation is that it makes the formula more detailed, and longer to calculate…

The Calculation

Hint: Don’t worry if this bit goes right over your head… just skip past to use the tool.

You take the two numbers as before (words per sentence, and percentage of long words), then add the five times the average sentences per paragraph. Since the target number for sentences per paragraph should be three, this will also give you 15. Then divide the sum of these three numbers by 2. The target is 15-25.

Clarity Rating Formula

The Online Tool

This obviously makes it more complicated to calculate manually, so there is a tool on this site that does it all for you. Just copy in a block of text – such as an e-mail message – and it will tell you how clear you are being.

This takes just seconds, and allows you to see the effect small changes can have on your Clarity Rating.

Click Here to Use the Clarity Rating Calculator

Limitations of the tool

You should be aware that there are a few limitations of the online tool.

  • The tool does not understand words. It only counts them. It will not take into account any ambiguous terms you use. You may get a good number, but your writing style is difficult to understand.
  • It defines a sentence as something between two period (.) symbols, so using contractions such as e.g. will confusion it.
  • You can sometimes get a rating that is in the target range, yet none of the component parts (word, sentence or paragraph lengths) are within their range. Therefore, you should aim to get each number within the range.
  • Some words are long, but they are pretty easy to understand. For example, the word “strengths” has nine characters, and only one syllable, yet would be considered a basic term.

Click Here to Use the Clarity Rating Calculator

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