Sep 19, 2026 ยท 6 min read
Running over is the most common way a good talk goes wrong, and it is the most avoidable. A slot is a number of minutes. Your talk is a number of words. The two are connected by one figure, your speaking rate, and once you know it, the length of the talk stops being a surprise.
Common guidance puts conversational English somewhere around 130 to 160 words per minute. Practiced speakers often sit near the low end on purpose, because a slower pace reads as calm and leaves room for the audience to think. Nervous speakers drift faster, which is how a talk that fit in the kitchen runs long on stage.
Your own number matters more than the range. Take a page of ordinary prose, about 300 words, open the stopwatch, and read it aloud at the pace you would use in front of people. Divide the words by the minutes. That figure, not the textbook one, is the rate you plan with. Most people are surprised by it in one direction or the other.
With a rate in hand, a slot converts to a word budget, and the word budget sets a ceiling on slides. Slide counts are the rougher column: one slide per one to two minutes is a widely used rule of thumb, and talks that lean on pictures run more slides than talks that lean on argument.
| Slot | Words at 130 to 160 wpm | Slides, rough guide |
|---|---|---|
| 3 minutes | 390 to 480 | 2 to 4 |
| 5 minutes | 650 to 800 | 3 to 6 |
| 10 minutes | 1,300 to 1,600 | 6 to 10 |
| 15 minutes | 1,950 to 2,400 | 8 to 15 |
| 18 minutes | 2,340 to 2,880 | 10 to 18 |
| 20 minutes | 2,600 to 3,200 | 10 to 20 |
| 30 minutes | 3,900 to 4,800 | 15 to 30 |
| 45 minutes | 5,850 to 7,200 | 20 to 45 |
The words column is the useful one. Written out, a 20 minute talk is about 3,000 words, which is a long essay. If your notes run to twice that, no amount of speaking faster will fit them in, and the cutting has to happen on paper before it happens on stage.
Five minutes holds one idea and one example. There is no room for an introduction that explains what you are about to say, so start on the idea itself. On the 5 minute timer each ring is 15 seconds, which is about one sentence, and the dial is worth a glance at the halfway point: if more than ten rings are gone and you are still setting up, skip to the example.
Class talks are usually graded on structure as much as content, so the time has to be visibly divided: a minute to frame the question, the body in two or three parts, a minute to close. Rehearse it with the 15 minute timer and note which ring you reach at each section boundary. On the day, those ring counts tell you whether you are ahead or behind without reading a clock.
Eighteen minutes became a standard through TED, and the constraint is the point: long enough to develop an argument, short enough that it has to be tight. Talks at this length are usually built around a single story or claim with a few turns, and rehearsed to the minute. The 18 minute timer is on the site for exactly this.
A 20 minute slot is rarely 20 minutes of talking. Assume a minute lost to setup and a few minutes for questions, and size the talk at 15. Speakers who plan for the full 20 are the ones the chair has to cut off.
The two tools answer different questions. A stopwatch tells you how long the talk actually is; a countdown tells you how much of the slot is left. Use them in that order.
For the first several run-throughs, open the stopwatch and press Lap at each section boundary. The lap list afterwards is a map of the talk: which section is bloated, which one is thin, and where the total lands. Cut from the sections that overrun, not evenly, and run it again until two consecutive runs land within about thirty seconds of each other. A talk that varies by two minutes between runs is not finished.
Once the length is stable, switch to a countdown set to the slot with the buffer removed, and rehearse against that. Now you are learning what the dial looks like at each section, which is the skill you use on stage.
A clock on the wall at the back of the room, or a phone face-down on the lectern, makes you break eye contact to check the time. A ring does not. It changes shape as time passes, and shape is something you notice at the edge of your vision without reading it.
Put the laptop or a phone where you can see it, open the timer for the slot, and take it fullscreen: press f, or use the enlarge control on the card. Fullscreen is the dial and the time and nothing else, in light or dark, so a single glance is enough and there is nothing on the screen to distract the front row if they can see it. On a 20 minute timer each ring is one minute, which is the natural unit for a talk; on the 15 minute one it is 45 seconds.
The timer stays silent while it runs. If you would rather not have the chime at all on stage, mute the device; the rings keep draining either way.
Questions are part of the slot, and they are the part you do not control. Plan them explicitly. For a 20 minute slot, 15 of talk and 5 of questions is a normal split. For a 45 minute lecture, 35 and 10.
The simplest way to hold that line is two timers, started together: one for the talk and one for the whole slot. When the first chimes, or the rings run out, you stop talking and open the floor. The second keeps counting through the questions, and when it is down to its last ring you take the final one. Two dials on one screen is one glance.
Finishing a minute or two early is a gift to the room and never counts against you. Do not fill it. Take the extra question.
Yes. Fullscreen it on a projector, or make a room from the homepage and share the link, and every open copy shows the same countdown while you control it.
Yes. The dial scales to the screen, and the rings read from the back of a room when the digits do not.