Last modified on April 9, 2012 by Brad Phillips

The Perfect Length Of A Presentation Is….

Twenty minutes.

At least that’s what new research from Maureen Murphy at the University of North Texas (UNT) suggests.

Author Susan Weinschenk, writer of the forthcoming book 100 Things Every Presenter Needs to Know About People, agrees. She points out that the terrific TED talks are usually 20 minutes long. “These same presentations stretched out to an hour might not be quite so brilliant,” she says.

But the mass media’s headlines about the research are overly-simplified. Inc. Magazine, for example, used this subhead: “Research shows there’s an ideal duration for a presentation. Exceed it at your peril.”

That might lead readers to conclude that no talk should exceed 20 minutes, but that would be a flawed conclusion that can lead to disastrous results. Still, this new research is a useful guide to speakers – so this post will help you use it to your advantage.

Should you really give audiences a break every 20 minutes?

First, here’s Ms. Weinschenk’s summary of the UNT research:

“Maureen Murphy tested this idea in an experiment. She had adults attending a 60 minute presentation at work, and tested to see the difference in memory and reaction to the same talk given in one 60 minute long presentation, versus a presentation that had 20 minute segments with short breaks in between. What Dr. Murphy found was that the people enjoyed the 20-minute chunked presentations more, learned more information immediately after, and retained more information a month later.”

 

She concluded:

“See if you can build in some kind of change every 20 minutes. For maximum learning you want a break every 20 minutes, as opposed to just a change of topic….Instead of taking one long break, take several short ones….I sometimes introduce short “stretch” breaks. These are anywhere from 2 to 5 minutes in length. I just announce, ‘Let’s take a short 3 minute stretch break’.”

 

I have a few takeaways from this research.

1.  It’s no surprise that shorter is better. Shorter and more focused presentations are more effective than ones that introduce too much information and delve into unhelpful detail.

2. There’s no such thing as an “ideal presentation length.” Inc. Magazine’s headline aside, you can exceed 20 minutes without it being “at your peril.” For example, if you’re an executive announcing layoffs to your staff, you’d probably want to stick around longer than 20 minutes to explain what the news means for employees and to answer audience questions. I have a tough time seeing how a “stretch break”  would work in that format.

The opposite is also true. Speakers would do their audience a disservice by stretching an eight minute presentation into a twenty minute one to meet some kind of “ideal” speaking length.

3. STILL…be mindful of these results when developing your next presentation. Ask yourself whether your presentation really needs to be an hour – the 20-minute version might be even more effective. And I like Ms. Weinschenk’s idea of “chunking” content into 20-minute bits.

But I’d argue that a short break isn’t necessary after every 20-minute chunk (in an eight-hour training workshop, that would result in as many as 18 mini breaks). There’s a middle ground here. Ms. Weinschenk writes:

“If you have activities, exercises, or interactions, plan them at 20 minute intervals. Although they are not true breaks, they allow people to assimilate the information just presented.”

 

I agree with that approach. Research has long concluded that students learn better through a combination of teaching approaches rather than having to endure an endless lecture. So if you’ve been lecturing for 20 minutes, show a video. Or ask your audience to share their experiences. Or divide the group into subgroups for a few minutes to complete an exercise.

So what is the ideal speaking length? The ideal speaking length is exactly the number of minutes you need to accomplish your goal, and not a minute longer. That’s not nearly as satisfying an answer as “20 minutes!” But since few things in life are accompanied by easy answers, I’d encourage you to view this new research as “useful information,” not as a hard rule you should always follow.

You can pre-order Susan’s book here. 

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A grateful tip of the hat to Deborah Brody (@DBMC).