https://insidegovuk.blog.gov.uk/2014/08/04/sentence-length-why-25-words-is-our-limit/

Sentence length: why 25 words is our limit

The information in this blogpost may now be out of date. See the current GOV.UK content and publishing guidance.

We recently blogged about our checklist for reviewing content and got a lot of questions about sentence length.

The Service Design Manual explains how people read and why sentences longer than 25 words aren't accessible.

In the style guide we’re now saying that if you have sentences longer than 25 words, try to break them up or condense them. If you can’t, make sure they’re in plain English.

When you write more, people understand less

GOV.UK should be an authoritative, trusted source. This means we need to write in a way everybody understands. We know people distrust jargon and that being clear and direct helps - as do shorter sentences.

Writing guru Ann Wylie describes research showing that when average sentence length is 14 words, readers understand more than 90% of what they’re reading. At 43 words, comprehension drops to less than 10%.

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.

People don’t read

Long sentences aren't just difficult for people who struggle with reading or have a cognitive disability like dyslexia or attention deficit hyperactivity disorder. They're also a problem for highly literate people with extensive vocabularies.

This is partly because people tend to scan, not read. In fact, most people only read around 25% of what’s on a page. This means it’s important to get information across quickly.

If it’s complex, make it simple

Long, complicated sentences force users to slow down and work harder to understand what they’re reading. This isn’t something people want to do, even if they’re familiar with the subject or language you’re using.

It’s easy to assume this isn’t the case for highly literate readers or people considered experts. Yet the more educated a person is, and the more specialist their knowledge, the more they want it in plain English.

These people often have the least time and most to read. Which means they just want to understand your point and move on, quickly.

Cut through the noise

It’s also important to think about how people access your content. They might be in a busy office, fighting for space on a crowded train or peering at their mobile in bed.

They don’t have time to deconstruct sentences and contemplate clauses, they just want you to get to the point. Doing this shows you respect your reader’s time, interest and attention.

If you write short sentences using plain English, it’ll help more people understand your content. And by making it more accessible, you won’t just help your busiest readers, you’ll open it up to people who might otherwise struggle to understand it.

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11 comments

  1. Comment by Jamie + Lion posted on

    hiya,

    How do you enforce the limit? Do you have an automated tool for text analysis?

    Cheers,

    Jamie + Lion

    • Replies to Jamie + Lion>

      Comment by Sara Vincent posted on

      Thanks for your question. We don't currently have an automated tool for checking sentence length. However, it might be something we look at in the future.

      We encourage people to use tools like Hemingway (www.hemingwayapp.com) to check the readability of content. This highlights both long and complex sentences.

      We also carry out regular spot checks on content, which involves checking how closely it follows GOV.UK style and principles. This helps us monitor content quality, and long sentences are generally counted as errors. However, we try to be consistent rather than uniform (www.gov.uk/design-principles#ninth), which means we understand the need to be flexible.

      Hope this helps
      Sara

  2. Comment by Cis posted on

    Just to prove that I have read, rather than scanned, this article, I am going to be picky.Your fifth paragraph is a bit mixed up because the statistics are not comparable.
    "Writing guru Ann Wylie describes research showing that when average sentence length is 14 words, readers understand more than 90% of what they’re reading. At 43 words, fewer than 10% do."

    Do you mean that when average sentence length is 14 words, 100% of readers understand more than 90% of what they are reading? Or do you mean that when average sentence length is 43 words, readers understand less than 10% of what they are reading?

    Cheers
    Cis

  3. Comment by Helen posted on

    I was interested to read this paragraph, and was immediately struck by the fact that the statistics didn't look right:
    "Writing guru Ann Wylie describes research showing that when average sentence length is 14 words, readers understand more than 90% of what they’re reading. At 43 words, fewer than 10% do."
    But looking at Ann Wylie's original article, what she actually says is:
    "Even at 14 words, they could comprehend more than 90 percent of the information. But move up to 43-word sentences, and comprehension dropped below 10 percent."
    Isn't Wylie saying that only 10% of the *information* is comprehended, not that only 10% of the people understand it (which is what your piece suggests)?

    • Replies to Helen>

      Comment by Sara Vincent posted on

      Hi Helen and Cis

      Thanks for your comments about the statistics. I've now corrected the post. Apologies for the confusion and thanks for pointing this out.

      Sara

  4. Comment by Andrew Fawkes posted on

    It's just my sense of homour, but I love the way the last sentence of this article is 26 words.

  5. Comment by Sara Vincent posted on

    Hi

    We aim to be consistent rather than uniform. This means recognising that every circumstance is different and being thoughtful about how rules are applied or adapted.

    The style guide say that if you have sentences longer than 25 words, try to break them up or condense them. In this case, I thought breaking up the sentence would be more problematic than keeping the extra word. I also used plain English to help make it clear.

    Thanks
    Sara

  6. Comment by Rob Finch (NHS Choices) posted on

    Any thoughts on paragraph length? Frequency of crossheads? I see you've stuck to a maximum of 3 paragraphs per section & 4 lines per paragraph.

    • Replies to Rob Finch (NHS Choices)>

      Comment by Sara Vincent posted on

      Hi

      We don't have strict rules relating to paragraph length or subheads. Instead, we try to think about readability and how to make content findable and understandable. To help with this, we recommend keeping to 1 thought per paragraph.

      Paragraph length is a little trickier. We recommend being concise, so find that paragraphs of 3-6 sentences work best. This isn't to say shorter paragraphs can't be effective, or that a complex idea may require additional explanation. However, if a paragraph strays off topic or looks too long, we'd suggest breaking it up.

      Subheads need to be considered carefully because users scan them to find out what a page is about and to navigate to specific information. This is why it's important to make them meaningful, and not clever or confusing.

      If a subhead is used every 3-5 paragraphs, it can also help users orient themselves as there will generally be one on their (desktop) screen. And if there's not, they won't have to scroll too much to work out where they are.

      Hope this helps
      Sara

      • Replies to Sara Vincent>

        Comment by Rowan posted on

        Looking at all the subheads here, they are just <p> with a <strong> nested inside them. Is there a specific reason for doing this rather than using H2's or starting <section> blocks with their own <header>?