Average Sentence Length and Readability Explained

Readability formulas such as Flesch Reading Ease and the Flesch-Kincaid Grade Level rely heavily on two numbers: average sentence length and average word length. Longer sentences and longer words make text harder to read.

Recommended averages

• General web content: around 15 to 20 words per sentence.
• Content for broad or young audiences: around 10 to 15 words per sentence.
• Academic or technical writing: often 20 to 25 words, but clarity still matters.

These are averages, not limits. A page full of seven-word sentences sounds robotic; variety keeps readers engaged.

Why long sentences are harder

Readers hold the beginning of a sentence in working memory until they reach the end. Each extra clause adds load. On mobile screens, a 40-word sentence can fill the whole display, making it easy to lose track.

How to check your averages

Paste your text into the word counter and look at Words / sentence in the details panel. Also check Avg word length: English prose usually averages around 4.5 to 5 letters per word. Much higher averages suggest heavy jargon.

Practical fixes

1. Find sentences over 30 words and split them at "and", "but", "which" or "because".
2. Move background information into its own sentence.
3. Use lists when a sentence contains three or more items with details.
4. Swap long words for familiar ones: "use" instead of "utilize", "help" instead of "facilitate".

Readability is respect

Clear writing is not "dumbing down". Experts also prefer text they can understand quickly. Lower reading effort means more of your audience reaches your main point, your call to action and your conclusion.

Frequently asked questions

What is Flesch Reading Ease?

Flesch Reading Ease is a readability score from 0 to 100 based on average sentence length and syllables per word. Higher is easier: 60 to 70 is roughly plain English. The related Flesch-Kincaid Grade Level converts the same idea into a US school grade.

How to improve readability?

To improve readability, shorten long sentences, use familiar words, break text into short paragraphs, add descriptive headings and use lists for steps. Check sentence length for readability by watching the words per sentence figure in our counter.

Short sentences vs long sentences: which is better?

Neither on its own. Short sentences are punchy and clear; long sentences carry nuance. A mix of the two gives rhythm. Problems start when most sentences are over 25 to 30 words.

What is the ideal paragraph length?

For the web, two to four sentences, or about 40 to 80 words per paragraph, is easy to read on phones. How many sentences in a paragraph depends on the idea, but one main point per paragraph is a good rule. Knowing how many words per paragraph you use helps you write for the web.