In fact, the average attention span among people who listen to speeches is estimated to be somewhere in the 5–1o minute span, and often towards the lower end of this. Thus it’s understandable that an insecure speaker will try to work with this, inserting a key point every five minutes or so to keep the attention of the audience from wavering. The average adult attention span has plummeted from 12 minutes a decade ago to just 5 minutes now, according to a sedianka.info article. If you can deliver your entire presentation in a total of 5 minutes or less, go for it; your audience will love you. Length of Presentation. The average attention span of an adult is 20 minutes. Implication: you should ensure that the first 20 minutes of your talk include any material that you want your audience to remember.