Thunder on the Way? Use This Simple Trick to Tell How Close It Is

You can learn this simple trick to measure the distance to lightning and thunder with no equipment at all.

What Happens When It Rumbles?

You’re sitting outside, clouds are gathering, and a loud thunderclap rolls across the sky.
You wonder: How far away is it, actually?
The answer doesn’t require any tech – just your ears and a little mental math.

Forget the 3-Second Rule – Here’s the Real One

When you see lightning: start counting seconds immediately:
One thousand one, one thousand two, one thousand three…
Stop counting when you hear the thunder.
Divide the number of seconds by 5 – that gives you the distance in miles.

Example: How to Do It

You see a flash of lightning and count 9 seconds.
9 ÷ 5 = about 1.8 miles away.
Want the distance in kilometers instead? Divide by 3.

Why Does This Work?

Light travels almost instantly.
Sound travels at about 1,115 feet per second (around 340 meters per second).
That’s why there’s a noticeable delay between lightning and thunder.
Counting seconds takes advantage of this difference.

When Is It Too Close?

Less than 10 seconds → under 2 miles away → go inside, especially in open areas.
Less than 5 seconds → very close → drop everything and seek shelter immediately.

A Fun Little Party Trick

Next time you’re with friends at a summer cabin, a festival, or the beach…
Use this trick when lightning flashes.
Impress them with the exact distance: “It’s 1.4 miles away – we’ve got five minutes!”