Understanding Readability

Apr 11, 2018 · 6 min read


Have you ever read a something and not been able to understand a single sentence? Or you are halfway down the page and have no idea what you are reading. The article, book, or newspaper is so complicated it seems only a Harvard PhD student could understand it.

That above thought is not what you want your instructor to be thinking when they read your essay, trust us. There is an art in crafting a clear, coherent argument and getting that argument across in a way that does not confuse the reader. But how can we know how complicated our essay is without sending it to ten friends and family members and getting their opinion? This is where Readability comes in — a score on the ease with which a reader can understand written text. Thousands of studies have been conducted on readability and many writers who write publicly attempt to make their work as readable as possible. After all, the easier your writing is to understand the broader your readership will be.

However, with university essays, this is not the primary focus. While you want your essay to have a good level or readability, you do not want the content to suffer because you have ‘dumbed’ it down. Explaining difficult concepts simply is a great skill, but you have to explain them fully. Simply keeping it at a high-level analysis has the potential to make your final grade for that paper suffer.

The man himself telling it how it is.

Readability Defined

Readability is defined differently depending on the context and the person explaining it. At Currikula we focus on the ease of which your essay is understood, or how complicated it is. In our Essay Analytics section, we display five popular readability scores from researchers in addition to our proprietary method explicitly derived for academic writing. The scores are determined by reading the whole text and either plugging the word count, sentence count, or specific words into a formula to retrieve a number — your score. Depending on which index is being used the score can have different interpretations.

How to Interpret a Readability Score

Each score has a method of determining the readability of your essay. Some indexes provide a score out of 100 and some score on a US grade level basis. Some indexes interpret a low score as more difficult to read, while others interpret a low score as easier to understand. To correctly interpret your score for each, you need to understand the context and what the index is calculating.

The Different Scores

There are dozens of indexes that measure the readability of a writing piece, which is why Currikula displays five third-party scores in addition to its own.

Flesch Reading

The Flesch Reading Ease score was created by Rudolf Flesch, a renowned researcher. It uses the following information:

  1. Average Sentence Length (ASL)
  2. Average Syllable Length (ASW)

The formula then computes the following:

Reading Ease Score = 206.83-(1.015xASL)-(84.6 x ASW)

Your score ranges from 0 to 100. A score of 0 is equivalent to that of US student in 12th grade, and a score of 100 is equivalent to a student in 4th grade.

The higher the score the more readable your writing is.


The Flesch-Kincaid model was developed again by Rudolf Flesch with Peter Kincaid for the US Navy to assess the difficulty in military technical manuals.

The information it uses is the following:

  1. Total words
  2. Total sentences
  3. Total syllables

The formula is then as follows:

0.39(total words/total sentences) + 11.8(total syllables/total words)-15.59

Your achieved score is that of a US grade level equivalent. For example, a score of 6 would mean it would require the skill of a US student in 6th grade to understand your writing. A score of 13 would be a first-year university level.

Unlike the Flesch Reading Ease, the higher the score the more difficult your writing is.


The Gunning-Fog index was developed by Robert Gunning in his readability consulting firm (yes, those actually exist). The second part of the name ‘fog’ comes from his idea that complications are like a ‘fog’ over a piece of writing.

The information the formula uses is as follows:

  1. Average sentence length (total words/total sentences)
  2. Amount of ‘hard’ words (words with more than two syllables)

The formula is the following:

Score = 0.4((average sentence length)+(hard words/total words*100))

Your score is, like the Flesch-Kincaid score, given as a US grade level.

Thus, the higher the score the more complex your piece is.


The Coleman-Liau index was developed by Meri Coleman and L.T. Liau and, unlike other indexes, relies more heavily on characters (letters, numbers, etc) rather than syllables. The advantage this system has is that computer programs can more accurately calculate characters than syllables (and let’s face it you are not going to calculate your readability manually).

The information it uses is as follows:

  1. Average characters per 100 words (L), calculated by (Characters/Words x 100)
  2. Average number of sentences per 100 words (S), calculated by (Sentences/Words x 100)

The formula is calculated as follows:

CLI score = 0.0588(L)-0.296(S)-15.8

Again, your score is calculated as the US grade level necessary to understand the writing.

Thus, the higher the score the more complex your piece is.

Automated Readability Index

Like the Coleman-Liau index, the Automated Readability Index (ARI) uses characters per word rather than syllables. It was designed for real-time readability monitoring on electric typewriters.

The information is uses is as follows:

  1. Average characters per word (ACW) (Characters/Words)
  2. Average sentence length (ASL) (Words/Sentences)

The formula is as follows:

ARI = 4.71(ACW) + 0.5(ASL)-21.43

Like the Flesch Kincaid, Gunning-Fog, and Coleman Liau it produces a score equivalent to the US grade level required to understand the writing.

Thus, the higher the score the more complex your piece is.


The Currikula Reading score tries to move away from word counts and sentence usage when calculating a reading score. It focuses on the difficulty of the words themselves, the flow of the text and how complex it is to string it all together when processing through a sentence.

We’re still fine tuning the algorithm and investigating how well the technology can be used to assess the authorship of essays. But hopefully we can explain more soon.

The higher the score the more complex the piece is. Around 20 is a university level.

Probably a solid Flesh Reading Ease of 15 here.

One score says my essay is complicated but the other says it is not?

Readability scores are not perfect, and you should treat them as such. Each index uses a different method of calculating your readability, so if Flesh-Kincaid says your writing is very complicated while Coleman-Liau does not then do not be alarmed. If all six (including Currikula’s score) determine your writing is complicated (above a grade 12 level), then there is a good chance your essay could do with some simplification.

How to make your essay more ‘readable’

You should not try to make your essay more ‘readable’ just to satisfy a particular readability score. However, there are some things you can do to make your argument more clear and concise. Currikula’s feedback section identifies unnecessary ‘weasel’ words which are extra words that often weaken an argument. Removing such words could make your argument appear ‘stronger’ while also reducing the number of words per sentence, thus improving general readability.

You can scan through your essay and reduce ‘wordy’ sentences. Currikula’s Essay Feedback will identify each paragraph that has excessive use of words, which can be reduced to improve your word count.

  • You can reduce the number of long words
  • Stop using long words for the sake of long words
  • Stop padding out sentences
  • Make sure to vary the length of your sentences. Having large amount of long sentences will no only decrease your readability but give the reader mental fatigue when reading your essay.


You should look at readability as the ability to communicate your idea in a clear and concise manner, not as satisfying a score. If you can get your point across in a ten-word sentence why use twenty?

The goal of an essay is to clearly argue your point, not demonstrate your ability to use a thesaurus. — Justin Moryto, Currikula Founder

With the above in mind, readability scores can be used as a general guide to making your writing easier to understand. So keep at it. With every essay, you improve you will be one step closer to getting a better grade.

This post was brought to you by the Currikula team. For more information about Currikula, please see our previous posts or visit www.currikula.com. You can create an account and use Currikula for free.

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