Siteimprove relates these word counts within a sentence to how difficult they are to read:
- Fairly difficult(Medium long sentence length): 21-25 words
- Difficult(Long sentence length) : 25-30 words
- Very Difficult(Very long sentence length) : 30-40 words
- Extremelydifficult(Extremely long sentence length) : 40+ words
Studies from the American Press Institute have shown that when the average sentence length is 14 words, readers understand more than 90% of what they are reading. At 43 words, comprehension drops to less than 10%. Long, complicated sentences force users to slow down and work harder to understand what they are reading. This is not something people want to do, even if they are familiar with the subject or language you are using.
Similar research from the American Press Institute shows that readers rate the following difficulty levels based on the number of words per sentence (*Sources: “Readers’ Degree of Understanding,” American Press Institute):
| Number of words per sentence | Difficulty level* |
|---|
8 words or less
| Very easy to read
|
11 words
| Easy
|
14 words
| Fairly easy
|
17 words
| Standard |
21 words
| Fairly difficult
|
25 words
| Difficult |
29 words or more
| Very difficult
|
Martin Cutts, the author of the book Oxford Guide To Plain English, offers the following guideline: “Over the whole document, make the average sentence length 15-20 words.” And what is the reason? He explains: "More people fear snakes than full stops, so they recoil when a long sentence comes hissing across the page."
Note: Some readability algorithms (LIX, SMOG, Flesch-Kincaid, Gunning Fog) ignore digits such as dates and phone numbers, while others include them (CLI, ARI). Therefore, the same sentence might not be considered "long" for all algorithms. Learn moreabout the different readability tests.
Additional resources for Readability
FAQs
The average sentence length is between 15–20 words. In most cases, the shorter the sentence, the better. This is because in today's age, many readers have shorter attention spans and want rapid information.
Why is it important to avoid using sentences of 25 words or more? ›
Rule of thumb: < 25 Words
They share this research: “Studies also show that sentences of 11 words are considered easy to read, while those of 21 words are fairly difficult. At 25 words, sentences become difficult, and 29 words or longer, very difficult.”
What is the ideal sentence length for readability? ›
Studies from the American Press Institute have shown that when the average sentence length is 14 words, readers understand more than 90% of what they are reading. At 43 words, comprehension drops to less than 10%. Long, complicated sentences force users to slow down and work harder to understand what they are reading.
Why does sentence length matter? ›
Vary Sentence Length to Engage Your Reader
Short sentences have punch and are a great way to emphasize important points. Longer sentences add rhythm to your writing. By using both short and long sentences, you add interest and drama to your writing that keeps your readers' attention.
Can a sentence be 30 words? ›
It is difficult to come up with a magic number or formula for determining when a sentence is too long. A 12-word sentence that minces words can be too long, while a crystal clear, beautifully-composed 22-word sentence is sometimes just perfect. In general, though, never go beyond 30 words.
Is a 22 word sentence too long? ›
Appropriate Sentence Length
Try to keep the average sentence length of your document around 20–25 words. This is a good rule of thumb to convey your meaning in a balanced way and avoiding a marathon or choppy sentences. The number varies as per the field, audience, or the nature of writing.
How does sentence length affect the reader? ›
Short sentences can show a faster pace or build up tension. Longer sentences can offer explanation and add detail.
What is considered a long sentence? ›
Studies also show that sentences of 11 words are considered easy to read, while those of 21 words are fairly difficult. At 25 words, sentences become difficult, and 29 words or longer, very difficult.
How do you know if a sentence is too long? ›
A sentence is too long if, upon reaching the end, your reader cannot remember how the sentence began. Writers are often advised to make sure that each sentence conveys only one idea; however, it can be difficult to decide what delimits “one idea,” especially when reporting results.
What is the rule for readability? ›
People tend to read three to four words per eye movement. It's a good rule of thumb not to have your reader make more than two eye movements per line, so limit your lines to six to eight words. Flyers, billboards, and posters will work best with short, bulleted points and plenty of white space. Use serifs.
Here is the golden rule to keep in mind for web typography: 45 to 80 characters (per line) is the ideal line length for text on websites.
What is the sentence length for readability guidelines? ›
Guidelines
- Make your average sentence 15 words long. The maximum sentence length for a good level of comprehension is 25 words. Split long sentences up into 2 or 3, or use bullet points. ...
- Avoid complex sentence structures. They are less easy to comprehend quickly.
While short sentences can convey clear and concise points, longer sentences can be used to communicate complex concepts in greater detail. Experts suggest using a combination of sentence lengths to make the paper more readable and keep readers engaged.
Are short sentences good or bad? ›
Shorter sentences are often much clearer than long sentences, which can easily 'go wrong'. However, it is probably not wise to use too many short sentences in academic writing, because ideas can appear rather disjointed. As a result, the writing loses fluency.
Can one word be a sentence? ›
A sentence word (also called a one-word sentence) is a single word that forms a full sentence. Henry Sweet described sentence words as 'an area under one's control' and gave words such as "Come!", "John!", "Alas!", "Yes." and "No." as examples of sentence words.
Is 20 words a sentence? ›
Research indicates that the ideal average sentence length is 15 to 20 words. When the average sentence length is 14 words, readers understand 90 percent of their meaning. Comprehension drops as sentence length increases.
How many sentences are 20 words? ›
20 words is about 1-2 sentences.
A sentence typically has 15–20 words.
Can a paragraph be 20 sentences long? ›
How Many Sentences Should a Paragraph Have? In general, paragraphs should have 5-8 sentences. In this case, if you're tasked with writing a five-paragraph essay, then you should want 25-40 sentences total. However, that's not a hard and fast rule.
Is a 25 word sentence long? ›
25 words is a good maximum sentence length limit. above 40 words sentences are hard to comprehend easily.
