Category: Reading

Readability Index – How good are you at writing?

All of us learn to read and write when we were in our elementary school. These two activities considered to be part of the very basic skill set of mankind. But the question is how good we are at reading and writing. Is there a systematic way to measure the reading and writing ability of a person? Is it possible to measure the readability in an objective way at all? Let us try to look in to these questions in detail.

If you look at a typical working day, a person may read and write many thousands of words per day. On the same line, there are many books being written every day. No of books being read by human population per day will be enormous. Let us look at some stats which I could found in the web.

Some Numbers

According to Google there are 129 million books written in this world. I think this stat was as at mid-2010 or earlier.

According to Verizon report in 2005, they estimate 2.25 billion emails per day. According to Radicati Group, there were 294 billion emails send per day.


You will probably agree with me that some books are easy to read and some books are not. The situation is same with the emails and any other document contain text. But the important question is what makes a book or an email easy or difficult to read? There seems to be many different views when it comes to answering the question.

It seems that readability depends mainly on the length of the sentence or no of words in the sentence. Also no of complex words being used in a sentence has an impact on readability. All of these factors can be objectively assessed and measured. (

There are factors which are subjective. The writing pattern has a very strong connection with the readability. For example how many examples you use in the text will affect the readability. Whether the text flows in a uniform direction (meaning that text in the start, middle and at the end is connected to the topic of the subject) is another factor. Whether you have a summary which explain the overall idea has a strong effect on readability. There are many other subjective factors which contribute to the readability.

Readability Index

OK, now back to the original question – Is there an index to measure the readability? To my surprise, there are not only one but many indices available. There are many organizations including Department of Defense USA using those indices to a good effect.  There are free online tools to measure the “Readability Index”.

One of the commonly used methods to assess the readability is the “Flesch–Kincaid readability test”. This test seems to be based on some empirical values as well as some parameters in your text such as “how much words per sentence”, etc.  Further details can be found in the following Wikipedia article.

Tools to Measure the Readability

Following are the some of the online tools which I found while searching the Internet which uses the F-K index.

What made to astonish was that Microsoft has inbuilt these rating into MS Word.  (May be MS have developed this feature to be used in their own documentation and somebody may have come up with the brilliant idea of integrating that tool to MS Word. Whoever it is, hats off to you.) I was missing such an important piece of information for this long. But the positive news is that now I can use the index to improve my writings. You can find the details in the following link.

One needs to understand that these indications are not perfect by any means. I couldn’t find a research on the accuracy of the online tools.

Let us now look at what these tools can do for us.

What can we do with these tools?

Can you recall the latest occasion where your email was not understood by the intended party? How many times you heard that “Sorry I understood it wrong”? It is not only emails which we encounter this situation. There are much more documents we write every day which contain text. How many of us complained that a requirement specification is difficult to understand?

All of these difficulties lead to many unproductive and frustrating hours at the office. If somebody converts the unproductivity to money, I am sure we are talking about billions of Dollars per year.

If we can use the above simple tools to check the readability our writing, we can save many billions of Dollars per year. Mind you, Microsoft has built the readability index to MS outlook as well. I really can’t understand why nobody promotes the idea and save quite many money.

When it comes to software engineering, it is not only about unproductivity. Imagine how many times we build a wrong piece of functionality due to the developers had readability problems in specifications. How much this world could have saved if somebody looked at the readability indices and their use?


It is up to us as professionals to use these indices and make our documents better. Anyone can save lot of money if bothered to check the readability of their documentation. The return will be immediate.

When it comes to software development, there is a different way to tackle the problem of readability. Agile methods promote the active discussions over the passive documentation with requirement owners. Still the writing is not something we can forgo today and I don’t think it will happen in near future. If there things are being written, there will be people who will read. Therefore it is our duty to improve our writing.

I wanted to test these indices while writing this post. This is how I improve my text. I use the Flesch-Kincaid Reading Ease score:

Reading Index Tool First Version Second Version Third Version Fourth  Version









MS Word





Some Information

# of Words





# of Characters





# of Paragraphs





# of Sentences





You can see that the three tools are not consistant when it comes to the values in the first version.  In the second version, I see that I have done some improvements in all the indices. I have added more text in the document but readability has gone up.

In my third version, I have decrease the readability. The post has grown. Since my second version is much more readabile, I need to improve the thrid version. With the forth attempt, I was able to increase the readability again. I got an average F-K grade of 8. That means this document can be understood by an average student. Fair enough rating for me. So I think I am done enough with the improvements and ready to publish.