The first time I gave a lightning talk, I had 10 slides and 5 minutes. I thought I was prepared.
I was on slide 4 when the host raised the red card.
The problem wasn't that I talked too much. The problem was I had no idea where I was in the talk while I was giving it. I was tracking my words, not my time. Those are completely different things.
What makes lightning talks hard
A 5-minute talk is not a shorter version of a 30-minute talk. It's a different format with different constraints.
You can't recover from a slow start. You can't do a recap. You can't save the good part for the end because there is no end — the timer just stops you.
The thing most people get wrong is treating the time limit as a soft guideline. It's not. When you run over in a lightning talk slot, you're not just going long. You're stealing time from the next speaker, disrupting the host's flow, and worst of all — people in the audience stop listening because they're watching the awkward exchange between you and whoever is trying to signal you to stop.
Running over is the only unforgivable mistake in a lightning talk.
The slide math problem
Here's something nobody tells you before your first lightning talk: your slides have to have a pace too.
10 slides in 5 minutes means 30 seconds per slide. That sounds obvious written out. It does not feel obvious when you're standing in front of a room and you've been on slide 2 for a minute and a half because someone asked a question.
So I built a timer that does the slide math for you. You put in your slide count, it tells you exactly when you should be moving to each slide. While you're presenting, it highlights the current slide you should be on in real time.
Open the Lightning Talk Timer →
No install. No account. Open it in a browser on your laptop, set your duration, enter your slide count, and start.
The five things I've learned about lightning talks
After running developer meetups and watching probably 80 or 90 lightning talks over the years, here's what separates the ones that land from the ones that don't.
One idea per talk. Not one topic. One idea. If you need a conjunction to describe what your talk is about, it's two talks. "How I use X and why I switched to Y" — that's two talks.
Start with the thing that surprised you. Not background, not context, not "so today I want to talk about." The first 30 seconds is the only time the audience is fully with you. Use it.
Slides are for the audience, not for you. If your slide has three bullet points, you're using it as a teleprompter. One image, one number, one phrase. The words come from you, not the screen.
Stop when the timer stops. Seriously. No "just one more thing." No "I'll wrap up quickly." The talk ends when the time ends. This is a skill you have to practice.
End with one thing they can do. "Google this." "Try this command." "Read this book." Give them somewhere to go. A talk that ends with "so yeah, that's pretty much it" wastes the only moment when the audience is actually ready to act.
Practice is the only preparation that matters
Reading tips helps a little. Running through your slides helps more. But the thing that actually makes lightning talks better is giving them with a real timer running and stopping when it goes off — even mid-sentence.
Do that a few times before the actual talk and the format stops being scary. You figure out what to cut. You learn which slides you rush through and which ones you linger on. The timer is honest in a way that your own internal sense of time never is.
I write about building, shipping, and occasionally talking in front of other developers at devkoan.substack.com
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