- Sentences
- 0
- Shortest
- –
- Longest
- –
- Variation (SD)
- –
Sentences over 25 words
Long sentences get a red wash here.
Length histogram
1–50
6–100
11–150
16–200
21–250
26–300
31–400
41+0
Longest sentences
Why sentence length matters so much
Every major readability formula uses average sentence length. In Flesch Reading Ease each extra word per sentence costs about one point, so cutting a 30-word average to 20 lifts the score by roughly ten. See it move in the Flesch formula lab.
The reason is working memory: a reader holds the start of a sentence in mind until the verb and object arrive. Long sentences with the main verb pushed late are the hardest. The fix is rarely to delete ideas. Split at conjunctions (“and”, “but”, “which”), turn parentheses into their own sentence, and put the main verb near the start.
Aim for variety, not uniformity
A standard deviation below about 4 words means your sentences are all roughly the same length, which reads flat. Short sentences create emphasis. Long ones carry nuance. Use both.
Sentence length FAQ
What is a good average sentence length?
For web content, an average of 15–20 words is a common target. Plain-language guides, including the UK Government Digital Service style guide, suggest keeping most sentences to about 25 words or fewer.
How long is too long for a sentence?
Sentences over 25–30 words become hard to follow on first reading, especially on a phone. Research summarised by the American Press Institute found comprehension drops sharply as sentences get longer.
Should all sentences be short?
No. A run of identical short sentences sounds choppy. Mix lengths: a long sentence that builds a point, then a short one that lands it. The histogram shows whether your rhythm has any variety.
How are sentences counted?
A sentence ends at a full stop, question mark, exclamation mark or line break. Common abbreviations (Dr., e.g., etc.) and decimal numbers don’t end a sentence. Headings and list items count as their own sentences.