About the Sound Distance Calculator
Distance to a sound source from the delay between seeing and hearing it — lightning, fireworks or echoes.
Also known as: lightning distance calculator, how far is the storm, speed of sound distance, thunder distance.
How to use this calculator
- Enter delay between flash and sound, air temperature.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
distance = speed of sound × delay, c ≈ 331.3 + 0.606 × T(°C)
Worked example
Using the values pre-filled in the calculator above:
- Delay between flash and sound = 5 s
- Air temperature = 20 °C
the calculator returns:
- Distance: 1.717 km
- Metres: 1,717
- Miles: 1.07
- Speed of sound at this temperature: 343.4 m/s