The magic number for paragraph and sentence length

Posted on 14 August 2015 by Emily Stella


Paragraphs: maximum of 7 lines (reports) or 5 lines (emails and letters)

The general rule is that a paragraph should contain one main topic. And this main topic is contained in what’s known as the topic sentence. So every time you want to introduce a new topic, start a new paragraph.

We recommend keeping your paragraphs to a maximum of 7 lines for reports and 5 lines for emails and letters. Not only will this help keep the reader focused on your writing but it will also provide a decent amount of white space on your page.

What do I mean by white space? I am always amazed to see a page in a proposal or report that is so dense with text that I don’t know where to start reading. By keeping your paragraphs short, you automatically create more white space, which makes the page less daunting and more inviting for your reader.

Keep your paragraphs short and embrace the white space!

Sentences: aim for 15 to 20 words

Sentences should ideally be between 15 and 20 words long and contain one idea. Any longer and you’re probably trying to pack in too many ideas. You’re also at (high) risk of losing your reader along the way.

The American Press Institute conducted an experiment a few years ago. They gave the same document to two groups of people with similar backgrounds. The first group were given a document where the average sentence length was 14 words. The second group received a document with average sentence length of 43 words. The content of the documents was the same.

The people reading the document with short sentences understood about 90% of the content. The group with long sentences, only 10%.

Cutting down your sentences forces you to think harder about your word choice, which will bring greater clarity to your writing. There’s also less room for making grammatical errors in short sentences.

Here’s an example:

Your holiday form needs to be completed at least two months before you plan to go on annual leave and once you have filled the form out, your line manager will need to sign the form and then you will need to take it to the HR department and have it signed by someone there to make it official.

Holiday forms needs to be completed at least two months before your planned trip. The form needs to be signed by your line manager and someone in HR to make it official.

Now let me read over this blog and check there are no super long sentences!