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Readability and SEO – Practical Tips for Authors and SEOs

When was the last time you read a text online and could not follow the content after just reading a few lines? You were probably a victim of poor readability. Today, we will show you how readability and SEO are connected and what you can do to make your text more understandable.

What is readability?

Readability is frequently confused with "legibility". But while legibility refers to the choice of typography and the spacing of words and lines, readability refers primarily to whether a text is comprehensible. How easy it is for someone to understand a text depends on the complexity of the sentences and the vocabulary used. The structural design of texts also has an impact on their readability.


Your readers' level of education is another important factor in whether they understand the content. A text by Goethe will be more readable for people with a high level of education or the ability to easily grasp complex sentence structures. Primary school pupils, on the other hand, will hardly understand these sentences, even if they know the characters and the language used in the text.

Therefore, readability is based on the one hand on the design of the content itself and on the other hand on the readers' capabilities. But how does this relate to SEO?

Why the readability of web texts is important for SEO

Internet users are somewhat impatient beings. They don’t give a website much time to load before they close it without having read a single paragraph. Even when the page loads fast, we want to know immediately what it is all about when we read online. We want to quickly grasp the meaning of a text, a paragraph or sentence. Naturally, the choice of medium has a great impact on this. Imagine, for example, that you sit at your home computer and look at a large screen. You have time because it is after work and you are looking for information about your next holiday destination. In this scenario, you will be much more patient than when you are on your way to work and quickly pull out your mobile in the subway to kill a few minutes by checking out some information for your upcoming holiday.

In general, mobile internet users are even more impatient than desktop surfers.

Since we quickly lose our patience online, a high bounce rate and a short dwell time threaten if web texts suffer from poor readability. This, in turn, is a negative sign for Google and other search engines. According to the search engine's interpretation, the user obviously did not find what they were looking for on the landing page. Therefore, the search engine assumes as default that the content of the URL is not good enough, which means that the page will not rank as highly as other pages in regards to a certain search term.


How to measure readability

As you have seen above, the readability of a text is, first‌ ‌of‌ ‌all, a subjective impression. However, this subjective impression determines which signals your users send to Google & co. It is therefore important for you as an SEO and author to be able to measure the readability of your text as objectively as possible.

There are different approaches to this objective measurement of readability. One well-known approach is briefly presented here:

Flesch Reading Ease Index (FRE)

The Flesch Reading Ease Index was developed in the 1940s by Rudolf Flesch at Columbia University. The objective of this index was to be able to determine the readability of a text by means of a formula. To this day, the Flesch Reading Ease Index is still regarded as the standard method.
The indicator is based on two metrics: the average sentence length (ASL) and the average number of syllables per word (ASW).

The idea behind this is, the longer the sentences of a text and the longer the words used, the more difficult the text is to read.

The FRE was initially applied only to English-language texts, but experts have now optimized and adapted the formula for other languages, as languages differ in the length of their words and sentences.

For German, the formula for determining the Flesch Reading Ease Index is:

180 – ASL – 58,5 x ASW

A scale from 0 to 100 is derived from this formula, with 100 standing for very easy readability at the student level. A FRE of 0 to 30 corresponds to difficult texts of a very high level that tend to be designed for academics.

As well as the Flesch Reading Ease Index, there are also other approaches to determine the readability of texts. The Flesch Kincaid Grade Level further developed the Flesch Index so that, with the help of the new formula, it is now possible to determine how many school years of education are required in order to be able to read and understand a text. This metric is mainly applied to English language texts.

Whether search engines like Google work with these metrics to determine readability has neither been officially confirmed nor denied. However, it is known that Google has been holding a patent, which is called "Gibberish Scores", since 2009. This makes it possible to recognize texts with little information content.

Some SEO tools such as the Yoast SEO plugin for WordPress utilize the Flesch Reading Ease Index to make it easier for authors and SEOs to write texts that are easy to read.

Factors influencing readability

You now know why readability is important for SEO. Next, we will show you what you can do specifically in order to write easy-to-understand online texts.

  • Sentence length: there is a simple rule for creating optimal sentence length: as long as necessary, as short as possible. Always keep your sentences as short as possible. Leave out superfluous filler words including phrases like “usually”, “actually” or “in principle”. Only ever use adjectives or adverbs if they are necessary. You don’t have to go as far as Mark Twain – he said: “If you see an adjective, kill it.” Still, in this case, less is more.

An example: "The beautiful T-shirt is normally available in blue and is particularly efficient for good sweat absorption."
If we get rid of superfluous and ambiguous wording, two short and crisp sentences result. They get straight to the point of the facts:
"This t-shirt is also available in blue. The fabric absorbs perspiration well."

Can you see the difference? In the second version, the product information was divided into two sets. At the same time, the wording is clear and easier for the brain to grasp when reading.

  • Sentence structure: subject, predicate, object, SPO. You should have learned this sequence at elementary school. At school, you learn to construct sentences as eloquently as possible. But not everyone is a Thomas Mann or James Joyce, who could construct sentences on a single page without repeating themselves. But however much you think otherwise: web texts are not world literature. This is simply about quick and easy understanding.

Therefore, even if it may annoy some language lovers, construct the simplest, neatest sentences using subject, predicate, and object. Avoid constructing sentences using long subordinate clauses. One subordinate clause is enough.

Text structure: what the Flesch Index and other readability tests fail to take into account is text structure. Even if you've been following all the tips so far, readability is not good if you don't use paragraphs, for example. Even without subheadings, a text seems to lack structure and is barely readable online.

Therefore, always divide your web texts up into meaningful paragraphs. You can use a new paragraph for each new subject. Also, use subheadings to highlight the subject of the next paragraph.

Text structure is also important from an SEO point of view. You should therefore have one h1 header per URL, and h2 and h3 tags for the other subheadings.

In this article, we show you how to use h-tags meaningfully.

Readability is also a question of style and tone.

Readability cannot be measured using indexes, because it depends not only on the structure and length of sentences but also on which words you use.
When writing about a certain subject, you may have done the research and relevant terminology, but what about the target group? Do they know the terminology, too? The same applies to foreign words. Do your readers know these terms, or need to look them up?

It follows from this that there is a further necessity for increasing web text readability: you really need to gear your texts to the target audience. After all, these people "must" be able to read what you have written. And remember - if users cannot grasp and understand a text quickly, they are likely to click elsewhere.

Detailed keyword research before you start writing is, therefore, a part of optimizing readability for SEOs and users. In selecting the "wording" you are taking the important decision right there that your words and sentences will also be understood.

In a further step, text readability can be improved. The key words here are "Rich Content", because images, videos or graphics can sometimes get to the core of a fact or subject much more quickly than many, many words.


How keyword stuffing and readability are connected

Anyone who has been active on the SEO scene for a few years can remember when briefings for text went: "we need text on the topic "buy cheap mobiles". The text should be 300 words long and include the keyword 10 times. "Now you can set up a simple computation. For this, you multiply the given keyword combination by 10 and get 30 words. Every tenth word you use in such text relates to the main keyword. Since the keyword specification does not correspond to usual word order in the sentence, integrating the combination exactly will in any case also make for awkward sentences and adversely affect readability. If this combination repeats after every tenth word, no normal person can draw anything meaningful from the text.

This explains how legibility and keyword stuffing are negatively related. Which in turn makes it clear why readability is important to SEOs.


As you have seen and read, readability and SEO are not mutually exclusive, but go hand in hand. The logic behind this is quite simple: write text for your users and not for search engines. And if you want to avoid scaring off your target group with huge sentences and long words, then write with added value on subjects that interest your users, so that they understand as much as possible. It's not about literary worthiness, but instead about a basic need for human communication and thus also marketing: the message needs to land.

In this sense: keep it short and simple.

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Published on Aug 26, 2019 by Philipp Roos