Why TED Talks Are 18 Minutes

Michael Metzger

TED Talks are making an impact. One reason is TED presenters speak for no more than 18 minutes. Scripture and neuroscience support this limit.

In scripture, the human job description is to “have dominion,” or proper power (Gen.1:26-28). That’s easy with car keys. They can’t resist when I pick them up. I have power over them. Dominion is different with people, however. They can resist. Dominion between individuals is shared. You have some, I have some.

This is ancient knowledge recently confirmed by neuroscience. Beginning in the 1980s, researchers at Harvard used neuroimaging to measure actual behavior change. They noticed a profound shift. Take communication. The old model was: if I initiate a conversation, I have 100 percent dominion over you the listener. I know what you “need” to hear. I know how long I “need” to talk. But researchers discovered there is no empirical evidence this approach is effective. It robs listeners of dominion.

Preaching is a form of communication. In the prevailing model, preachers have all authority over what congregants “need” to hear and how long a sermon needs to be. If people afterward say they loved the sermon, it was effective. Lives are being changed.

Not true. Harvard researchers discovered there is no empirical evidence this approach is transformational. For example, immediately after a sermon, listeners only remember 50 percent of what was said. By the next day it drops to 25, and a week later, 10. The percentage actually doing something about a sermon is even lower.

The more effective model is sharing authority. You have some, I have some. If we apply the Harvard research to preaching, we see that effective preachers discern how much actual authority they have versus how much authority listeners have. They do this by measuring how long listeners pay attention before they tune out. Effective preachers recognize people can hear a sermon but not be listening (teens are quite adept at hearing but not listening). In fact, there are limits to how long people can listen.

What are those limits? Neuroscientists are identifying how long most people can pay attention before they tune out. The range seems to be in the area of 10 to 18 minutes. TED organizers reached the conclusion that 18 minutes works best. Nobody, no matter how famous, wealthy, or influential is allowed to speak more than 18 minutes on a TED stage—it doesn’t matter if your name is Bill Gates, Sheryl Sandberg, or Bono.

TED’s 18-minute rule works because the brain burns energy, consuming lots of glucose, oxygen, and blood flow. As the brain takes in new information and processes it, millions of neurons are firing at once, burning energy and leading to fatigue. Researchers at Texas Christian University are finding that the act of listening can be as equally draining as thinking hard about a subject. Dr. Paul King calls it “cognitive backlog.” Like weights, the more information we are asked to take in, the heavier and heavier it gets. On average, after 18 minutes, we drop it all, failing to remember most of what we heard.

This is why TED curator Chris Anderson says 18 minutes “is long enough to be serious and short enough to hold people’s attention.” He adds, “By forcing speakers who are used to going on for 45 minutes to bring it down to 18, you get them to really think about what they want to say. It has a clarifying effect. It brings discipline.”

Preachers could use some of this discipline. This is the time of year when pastors map their fall preaching calendar. Why not also map how long they preach? On average, the most popular evangelical pastors preach twice as long as a TED speaker. Why?

Culture. Seminary culture, mainly. I know this firsthand. I’ve preached over 650 sermons. I was trained in two seminaries. I’ve taught preaching in two seminaries. The prevailing seminary culture assumes sermons must be 30-, 40-, 50-minutes. But seminary profs never told us why.

It’s helpful to remember culture is simply what people are accustomed to. When Henry Ford introduced the assembly line, he recognized it was dehumanizing. He knew a few workers would quit in the first year. Ford missed the mark—913 walked off the job. So he raised wages and kept rehiring, hoping Ford workers would get used to it. They did.

I’m not saying 30-, 40-, 50-minute sermons are dehumanizing. I’m saying they don’t fit human nature. They don’t share dominion (you have some, I have some). And they’re not transformational. The preachers I know have hearts of gold and mean well. They want to preach transformational sermons, but when they go past 18 minutes, the transformational impact drops like a rock.

It’s difficult to seek the flourishing of the city if a sermon doesn’t yield a flourishing faith. Sermons that exceed 18 minutes don’t produce human flourishing faith. Effective communicators recognize this. In 15 minutes, John Kennedy inspired a nation to go to the moon. In a 15-minute TED talk, Facebook COO Sheryl Sandberg inspired millions of women to “lean in.” Steve Jobs gave one of the most popular commencement addresses of our time at Stanford University and he did it in 15 minutes. Simon Sinek’s 18-minute 2009 TED Talk has been viewed by almost 40,000.000, launching the “Start With Why” movement. These talks are transformational.

I know preacher want to transform lives. That requires the congregation pays attention. Human nature indicates there are cultural limits to how long listeners can pay attention. I’m generally not prescriptive, but if it’s no more than 18 minutes, shouldn’t preachers cap sermons at 18 minutes?


Morning Mike Check


The Morning Mike Check

Don't miss out on the latest podcast episode! Be sure to subscribe in your favorite podcast platform to stay up to date on the latest from Clapham Institute.


  1. Great information, thankfully it took me less than 18 minutes to read your column.
    When I train, which is my business, I use the CPR concept: Content, Process, Review. In short it says that every 20-30 minutes I go through the CPR cycle: Content, Process and Review. My thumb-rule is no more than 8 minutes of presentation or content by me at a time, then I specify an exercise or table discussion that allows everybody to Process the information. I didn’t know that 18 minutes was the optimum time, to be on the safe side, I’ll stick with 8 and my occasional droning on to 10. After all, I know I’m no Bill Gates or Bono!
    Another thing I know is that a lecture is the fastest way known to man to get the information from the notes of the teacher to the notes of the student without passing through the brain of either one of them. Alas, now I know why I never learned much in those History of Seapower LECTURES during Plebe year at USNA……

  2. Brad:

    You join a long line of Christians were satirists – G.K. Chesterton, for example! They poked fun at our fallenness by poking our funny bone.

    Stick with 8 minutes, as the range of effectiveness is 10-18, and you, as you note (and I know), are no Bill Gates or Bono.

  3. Mike,

    Thanks for challenging us about the limits of talking. I especially resonated with connecting your insights to shared dominion. As I read I reflected on liturgy as literally “the work of the people” or “works of faith”. It seems to me a big problem in churches today is that many churches’ liturgies also fail to share dominion. Church goers are primarily consumers of rather than participants in. This is reflected by long sermons and anemic liturgy (song preaching song sandwhiches). In my own church journey, I’ve moved back in time to a more ancient tradition that invites me into participating in and under a liturgy that doesn’t mindlessly adopted a consumer mindset from the secular world (ie the stereotypical mega church and youth group entertainment complex). I think you would agree our liturgy and how we participate outside of the sermon is just as important if not more important than the sermon itself.

  4. On the other hand…my life has been changed in many ways via professors, pastors, politicians and business leaders who took much longer than 18 minutes to get me to wrestle with meaty, life-changing, issues. They have left me spell-bound, challenged, and with an abundance of questions that had me motivated to follow up with an in-depth inquiry.
    I am concerned that our modern-day over-exposure to television and social network formats may have unconsciously shortened our attention spans in such a way that we are inclined to “check out” after just a few moments if the program does not grab our attention.
    I am not ready to abandon the college lecture, the 35-40 minute sermon, or even the political speech of 60 plus minutes. I am hesitant to constrain these orators to 18 minutes and am willing to work hard at understanding complexity, nuance, etc. that often cannot be easily reduced to the soundbites that a shorter format demands.
    However, I am in great admiration of well-crafted, concise, wordsmithing. It is hard not to admire the power and brevity of Lincoln’s Gettysburg address.

  5. Tim:

    I understand your hesitancy. But according to “Brain Rules,” impactful speeches like Lincoln’s are wrapped around a metaphor and rather brief (long-term memory retention increases to 60 percent from ten when a speech features one central metaphor. One, not many and not none). The Gettysburg is wrapped around one central metaphor (rebirth of the nation), restated five different times.

  6. Lots to think about here. Shared dominion makes sense. I wonder about the difference between the built-in, physiological limits of the audience and self-imposed, or self-conditioned ones. It seems attention span is a product of both. And as with other physiological limits, like running a four-minute mile, attention span can be improved upon with practice or atrophy with neglect. It seems the Bible has both–communication that condescends to our limits and poor choices, but also communication that demands more than what is comfortable–all our heart, soul, and strength–if we are to know it’s treasures. Since God typically communicates through means, like preachers, I wonder how we accommodate the 18-minute rule without creating a subtext that the audience also has a right to demand God communicate in a certain way–that He must meet my accessibility standards. I believe Neil Postman makes this point, or at least a similar one, in “Amusing Ourselves to Death.”

  7. Great points, Eric. Accommodation seems to be the right word. God accommodates in communicating with us (unless The Father, Son, and Spirit spoke Hebrew in eternity past). God also accommodates in giving us, finite beings, finite glimpses of infinite reality. For example, a full-blown face-to-face would evaporate us.

    As you said, lots to ponder. This, again, from a man (me) not given to a prescriptive faith. But then again, Jesus is the only way, so prescriptions like time limits are not necessarily bad.

  8. A dear friend forwarded your TED-related blog posting. (h/t Bill Peel!).

    Great article. I’d love to connect on this topic, as I’m rounding the bend on launching a new training curriculum for pastors, based on TED Talk speaker training.

    Yep, I’ve some answers backed up by research… And yet, the learning curve is unending. Example: I’m off to Asbury Theological this week. Gordon-Conwell for the National Preaching Conference the following week. My team just received the results of a BARNA GROUP Pastors Poll that we commissioned, exploring how pastors see and interact with TED. Particularly striking, is the “swipe left” attention span of younger generations–whether in the classroom, a conference room, or… a church.)

    I completely affirm your call for shorter sermons. To impact lives, they much be processed and shared. Another key TED best practice is clarity in message and “The Rule of 3” (no more than 3 points–which is also undergirded by research. Alas, many of my dear friends from seminary habitually break those guidelines. Another the key differentiator–even for longer sermons is to ensure they are story-wrapped. Not examples, illustrations, vignettes–but real, personal, authentic, narrative-arch story. Again, a regular miss.

    Blessings–and again, a great thought piece!

    Founder, myTEDtalk.com, mySHORTtalk

    PS. An example of a great 12-minute TEDx Talk follows. Dr. Waldinger is an alumni client. At 22M+ views (in under 3 years time), his talk is the 10th most-viewed talk in the history of TED.com.

  9. I recall reading many years ago in a text on biblical preaching and teaching that Jesus’ “Sermon on the Mount” was likely His stock sermon or core public message. He would routinely present it to audiences as He traveled around Israel as an itinerant Jewish rabbi.

    The book went on to say that if you read Matthew 4-6 aloud at a comfortable pace, Jesus’ Sermon on the Mount takes about 18 minutes. Coincidentally, research in human behavior was showing that 18 minutes is the attention span of a typical person. This research was done and reported decades ago — long before social media and today’s non-stop entertainment culture conditioned us.

    That 18 minute target seems to be a natural limit, hard-wired into us. As the text humorously asked, “If Jesus said what He needed to in 18 minutes, what do you have to say that is so much more important?!”

    Obviously, different contexts, purposes and audiences may require differing approaches. But I think that when it comes to preaching, “Less is more.” I tend to be tolerant of 40-50 minute messages, whereas my very astute wife reflexively tunes out after 30 minutes.

    As an evangelical, my sense is that our church services overvalue the clear importance of teaching the Word while undervaluing other elements of worship, particularly the aesthetic and sensory aspects (creative music, visual beauty, textures, scents and experiences).

    Looking back on decades of teaching in a variety of contexts, I notice that I’ve migrated towards talking less (time-wise) while saying more. Apparently, wisdom and maturity can enlighten even the likes of me!

  10. Kent: I always appreciate your astute comments. I share your sense that evangelical services overvalue teaching the Word while undervaluing other elements. Thank you for chiming in.

  11. I agree that “prescriptions like time limits are not necessarily bad” – and that the discipline of constraining a talk to a time limit is usually a good thing! It sharpens the thought, and polishes the presentation.

    I wonder how Neil Postman’s work would fit in here, though, describing our relentless slide away from attention to the fragmented “Now, this. . . .”

    I appreciate the discipline Tim describes that is needed to really dig in and think about important ideas. I’m thinking that perhaps it is that discipline and thinking (by me, the hearer) that is the interactive part of the ‘shared authority’ you were speaking of. To that end, perhaps we should be focusing instead on the ‘shared authority’ bit – and emphasizing the responsibility of the hearer to engage with what is heard. I’ve always loved the fact that, in Hebrew, the word sh’ma means both to hear and to obey. . . . And that lamad is both teach and learn. In the Hebrew, our responsiveness is almost an assumption of the language itself!

    Anyway, my biggest fear is that touched on by Garret, that we limit the word to 18 minute or less sound-bites that we still are not responding to. That leads us to being peppered with more and more smatterings of “activities” – be they “now turn to your neighbor and ________” or “Stand with me, and let’s sing our praise to the God who _______” or “Under your chair, you will find a response card. Take a minute of silence to ______ and then _________” all of which continues the usurpation of dominion and undermines authentic response. We’re still being told what to do, rather than voluntarily inhabiting and participating in a <joint liturgy, for example, that we’ve all grown up with and embraced.

    There’s more for me to think about, there. . . . So I’l shut up now! Thoughts?

  12. Marble:

    I hope, as you put it, you never shut up.

    There might be a fallacy in our thinking. More is better. More time given to a sermon yields more content for more transformation. What if that syllogism is false?

    If, as Kent notes, Jesus’ standard message was 18 minutes, and 18 minutes has always been the norm (I know – I can’t prove it – just go with me), then the assumption of a “cultural slide” is false.

    The Enlightenment model is head to heart to hands. But what if that is exactly backward? What if it’s hands to heart to head? “It is by having hands that man is the most intelligent of animals,” wrote Anaxagoras. Hands-on learning and knowledge are superior, as in “Adam knew Eve” (Genesis 4:1). What do we imagine is going on there?

    We’re trying to cram too much learning into the sermon. The Lexio Divina seems to be a better way to learn. Based on the central Hebrew word “return,” we keep returning – through prayer, confession, a song or hymn, sacrament, sermon, worship, our offerings – to one central idea (mainly communicated through an image or metaphor) throughout the service. It gives participants an experience of “tom,” the Hebrew word for “one,” or integer, or seamlessness.

    The lecture format was introduced until the 14th century. The didactic approach to sermons (reading from notes) didn’t become until the 19th or 20th century. Maybe their time is up. Not because of a “relentless slide” in paying attention as much as inflicting on listeners an Enlightenment approach that, over a few centuries, becomes one that left-brained people have learned to happily endure.

  13. What if…

    What if actually exchanged dominion was gauged as not only comfortable but completely compelling at long past 18 minutes each? Then what might actually be the subject of the examination is not just the content of the words or the brain’s endurance but the humanness of the exchange – the looking into each others’ eyes, our sight of each other’s face and hair and clothing – the beholding each others’ of “person-ness.”

    And then when you want and crave exchange and it’s not exchanged dominion but domination, and you keep expecting shared exchange and it’s not – the very same sights and smells of the human across from you are now grotesque and hideous.

    These are my experiences – are they yours? Neurological studies or not, I think that what such studies might be are thin strands of hair-like connections to what it means to be captured by another’s god-like humanness – and how we’re repulsed by death, decay, and inhumanness – including death-like domination. Corollary – Maybe foreplay is best at 17 minutes?

Leave a Reply

Your email address will not be published. Required fields are marked *