# Does anyone know how to calculate the distance where a lightning has struck? Answered

I remember when I was a child we learned how to calculate the distance where a lightning has struck by counting the seconds between the time we saw the flash until we heard the thunder. I forgot the number that we multiplied the time by ( I think is the speed of sound). I thought about this after we had a nasty thunderstorm. Does anyone know?

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Sound travels at 768mph (in dry air at 20o in a storm it'll be a bit different). 1 second = ~1/5th of a mile, so 5 sec = ~a mile.
But be aware that strikes from high altitude are going to throw the ground-contact point off a bit and you can't measure short periods of time very accurately - it's a rough guide.

L

Count the number of seconds from the time you see the lightning flash until you hear the first rumble of the thunder. Divide the number of seconds by 5 to calculate the distance in miles (or divide by 3 for kilometers)
The result is a fairly good approximation of the distance away from you.