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Science Calculators

Thunder Distance Calculator

Verified formula Updated Jun 2026 Private — runs on your device

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Verified formula Private

Distance to lightning

1.715

In metres
1,715

For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.

How to use the Thunder Distance Calculator

The Thunder Distance Calculator works out your distance to lightning, along with 1 related figure in an instant. Enter seconds between flash and thunder and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.

  1. Enter the seconds between flash and thunder.
  2. Read off your distance to lightning, together with in metres — the calculator updates automatically, with no button to press.

Formula

The Thunder Distance Calculator uses the formula:

Distance to lightning = Seconds between flash and thunder × 0.343

Worked example

For example, with seconds between flash and thunder of 5, the distance to lightning is 1.715.

Inputs used
Seconds between flash and thunder 5
Results
Distance to lightning 1.715
In metres 1,715

Results are estimates for educational use, not professional advice.

Frequently asked questions

Multiply the seconds between flash and thunder by the speed of sound (343 m/s). 5 seconds is about 1.7 km.

Light arrives almost instantly, but sound travels much slower, so the gap reveals the distance.

Roughly. Sound covers about 343 m a second, so about 3 seconds per kilometre.

If thunder follows the flash within about 30 seconds (10 km), seek shelter immediately.

The Thunder Distance Calculator uses the formula: Distance to lightning = Seconds between flash and thunder × 0.343. For example, with seconds between flash and thunder of 5, the distance to lightning is 1.715.

Enter the seconds between flash and thunder. Read off your distance to lightning, together with in metres — the calculator updates automatically, with no button to press.

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