Thunder Flash-to-Bang Calculator
Lightning light travels at 299,792 km/s (instantaneous to human perception), while thunder travels at approximately 343 m/s (1 km every ~2.9 seconds). Count the seconds between the flash and bang to calculate strike proximity.
Storm Observation
Rule of thumb: 5 seconds ≈ 1 mile (1.6 km).
⚠ 30/30 Storm Safety Rule:
If time between flash and bang is under 30 seconds, you are within 10 km (6 miles) — lightning can strike. Seek enclosed shelter immediately.
Calculated Strike Distance
Kilometers Distance
1.72 km
Miles
1.07 miles
Feet
5,630 ft
Cite This Calculator
GemsMakers Meteorological Acoustics Lab. (2026). Thunder Distance Calculator & Flash-to-Bang Safety Rule. GemsMakers.com. https://gemsmakers.com/thunder-distance-calculator.php