Passive Voice Checker
Highlights passive sentences, shows the passive share and who did the action.
20 words and 25% are the Yoast SEO plugin defaults for English, not a Google rule. Paragraphs over 150 words are flagged, following digital.gov.
Result
0Average words
0Long sentences
0Longest
| Words | Sentences |
|---|
The free sentence length checker counts the words in every sentence, shows your average and highlights the sentences that are long enough to lose a reader. It also flags paragraphs over 150 words. Everything runs in your browser.
Quick answer
A sentence length checker splits text into sentences, counts the words in each and reports the average, the longest sentence and the share above a limit. There is no Google rule for sentence length. Plain language guidance says to express one idea per sentence, and many writers use about 20 words as a soft limit.
What is a sentence length checker?
A sentence length checker is a tool that measures how many words each sentence contains and points out the long ones. Long sentences are not wrong, but they make the reader keep several ideas in mind before the full stop. Digital.gov's clear and short guidance says to "express only one idea in each sentence" and warns that "sentences loaded with dependent clauses and exceptions confuse the audience".
This checker gives you numbers to act on: the average words per sentence, how many sentences pass your limit, the longest one and a simple distribution. It also checks paragraphs, because digital.gov notes that writing experts recommend paragraphs of "no more than 150 words in three to eight sentences".
How do you use the Sentence Length Checker?
- Paste your text. Leave a blank line between paragraphs so the paragraph check works.
- Set the long sentence limit. The default is 20 words.
- Set the share of long sentences you accept. The default is 25%.
- Read the highlighted text and the list of the 5 longest sentences.
- Split the longest sentences into two, then paste again to see the new average.
How long should a sentence be?
There is no single correct length. Plain language guidance from digital.gov does not set a word limit for sentences; it says to express one idea per sentence and to break complex ideas into parts. The Yoast SEO plugin uses 20 words and a 25% share as its English defaults, which is why this tool starts there. Mix short and medium sentences so the text has rhythm.
Does sentence length affect SEO?
Google does not publish a sentence length rule, and its helpful content guidance even lists aiming for a word count as a warning sign. What Google does ask is whether content is clear and well produced. Shorter sentences help readers, and they also make clean, quotable answers that AI search tools can lift, which matters for AEO.
How do you shorten a long sentence?
Find the joins. Words like and, which, because and while often mark where one idea ends and the next starts. Cut there and start a new sentence. Turn lists inside a sentence into a bullet list. Remove filler such as "in order to" and "it is important to note that". Then read it aloud: if you need a breath in the middle, it is still too long.
Quick reference
| Words per sentence | How it reads | What to do |
|---|---|---|
| 1 to 10 | Punchy, easy | Good for key points and instructions |
| 11 to 20 | Comfortable | Ideal for most body text |
| 21 to 30 | Demanding | Split if it holds two ideas |
| 31 or more | Hard to follow | Split or turn into a list |
| Paragraph over 150 words | Wall of text | Break into 2 or 3 paragraphs |
Worked example
Example
Example: the default text has 6 sentences and 78 words, so the average is 13 words. Two sentences are over 20 words: one of 28 words about long sentences and one of 30 words about the audit, so 33.3% of sentences are long, above the 25% limit. Splitting the 30 word sentence into "This page explains how our technical SEO audit works and what we check on every URL." and "It also covers how long the work takes and what you receive." brings the long share down to 1 of 7 sentences, 14.3%.
Learn more
Frequently asked questions
How does the tool decide where a sentence ends?
It splits on full stops, question marks and exclamation marks. It protects common abbreviations like e.g., i.e., Dr. and U.S., and decimal numbers like 3.5, so they do not end a sentence early.
Why is my average different from another tool?
Tools split sentences and count words in slightly different ways, especially around abbreviations, numbers, lists and headings. Use one tool consistently and compare your own drafts, rather than comparing scores across tools.
Are headings and list items counted?
Only if they end with punctuation or run into the next line. Paste body text without headings for the cleanest result. A list item without a full stop joins the next sentence and can look longer than it is.
Is a 20 word limit a Google rule?
No. It is the default in the Yoast SEO plugin for English. Google sets no sentence length limit. Treat 20 words as a prompt to check a sentence, not a rule that every sentence must follow.
Is my text uploaded?
No. The checker runs in your browser using JavaScript, so your text never leaves your device. You can check drafts, client copy and unpublished pages safely.
What about very short sentences?
Short sentences are fine and often add emphasis. A text made only of very short sentences can feel choppy, so mix lengths. The distribution table shows whether you rely too much on one length.
Sources
Checked 22 Oct 2026. Facts checked against these official pages. Read how I check facts in my editorial policy.