Tap Start when you see lightning, Stop when you hear thunder. Repeat to track the storm’s trend.
This free Lightning Distance Calculator App (sometimes called a lightning timer or thunder distance calculator) helps you quickly estimate how far away lightning is using the flash-to-bang method. It works instantly in your browser no download or separate lightning distance app required.
How The Lightning Distance Calculator Works
Many people call this method the flash-to-bang rule, or use it as a simple lightning delay timer. By timing the seconds between a flash of lightning and the sound of thunder, the calculator estimates the lightning strike distance. Divide the seconds by 5 for miles, or by 3 for kilometers, to find out how far the lightning is.
Safety: This tool is informational only. Lightning can strike unpredictably. Follow official weather guidance.
Frequently Asked Questions
How Accurate Is the Lightning Distance Calculator?
The calculator provides an approximate distance based on sound speed. It’s a reliable guide but not exact.
Can This Calculator Show Lightning Distance Near Me?
No GPS is used. It measures based on your timing of the flash and thunder, not physical location.
Do I Need a Lightning Distance App or Download?
No. The calculator works in your browser, so there’s no need to install a separate app.
What’s the Difference Between a Lightning Timer and a Lightning Distance Calculator?
They’re the same concept. Both terms describe the flash-to-bang method to calculate distance.
Why Do You Divide Seconds by 5 for Miles and by 3 for Kilometers?
Sound travels roughly one mile in about five seconds—or one kilometer in about three seconds—under average conditions.
What If I See Multiple Flashes in a Row—Which One Do I Time?
Time the first clear flash you see with its matching thunder. Multiple close strikes can be confusing; pick the clearest event.
What If I See Lightning but Don’t Hear Thunder (or Vice Versa)?
If thunder isn’t audible, the strike may be too far away. If you hear thunder but don’t see the flash, it may be obscured by clouds or distance.
Do Wind, Temperature, or Terrain Affect the Accuracy?
Yes, slightly. Air conditions can change how sound travels, but differences are usually small for everyday use.
Why Is My Result Different From a Weather App or Radar?
This calculator uses your timing of sound delay at your location, while weather apps use radar and lightning detection networks. Both are valid but draw on different data.
Can I Use the Calculator Indoors or Through a Window?
Yes. If you can see the flash and hear the thunder, the method works whether you’re indoors or outdoors.
Can I Use the Lightning Distance Calculator Offline?
A live web connection is required for the app. Offline, you can still use the manual rule: count the seconds between flash and bang, then divide by 5 for miles or by 3 for kilometers.