Speaker Delay Calculator
Enter a distance to get the time sound takes to travel it (the delay time in ms), or enter a delay time to get the distance. The speed of sound comes from the air temperature, in °C or °F.
How the delay time is calculated
The delay time is the time sound takes to travel the distance.
- Delay time (seconds) = distance (m) ÷ speed of sound (m/s)
- Distance (m) = speed of sound (m/s) × delay time (seconds)
The tool shows the delay time in ms (milliseconds, a thousandth of a second).
The speed of sound
The speed of sound is calculated with this approximate formula:
- Speed of sound (m/s) ≈ 331.5 + 0.6 × temperature (°C)
It gives 343.5 m/s at 20 °C (68 °F) and 331.5 m/s at 0 °C (32 °F). This formula uses the temperature only; humidity, pressure and wind are not considered. It is a value for air, and the real speed of sound varies a little with those conditions. Compared with a more exact formula, the difference is about 0.2% or less between −20 °C and 40 °C. You can enter temperatures from −50 °C to 60 °C (−58 °F to 140 °F).
Entering the temperature in °F
If you choose °F, the temperature is converted exactly to °C with °C = (°F − 32) × 5 ÷ 9 before the speed of sound is calculated. The line under the temperature box shows the temperature used in both units, so you can check that the unit you chose is the one used. For example, 32 °F is 0 °C and 68 °F is 20 °C, and they give the same result as the same temperature entered in °C.
Examples
- 10 m at 20 °C (68 °F): 10 ÷ 343.5 = about 0.02911 seconds, or about 29.11 ms (about 2.91 ms per meter).
- 15 m at 20 °C: about 43.67 ms.
- 10 ms at 20 °C (delay time to distance): 343.5 × 0.010 = 3.435 m.
- 1 ms is about 0.3435 m (34.35 cm) at 20 °C.
- 10 m at 0 °C (32 °F): about 30.17 ms. 10 m at 40 °C (104 °F): about 28.13 ms (sound arrives sooner when the air is warmer).
Units of distance
You can enter the distance in meters, feet, centimeters or millimeters. 1 m = 100 cm = 1,000 mm, and 1 ft = 0.3048 m (by definition).
Notes
- The distance can be 0 or more, with decimals (up to 12 digits before the decimal point and 6 decimal places). The delay time is the same. Use a period as the decimal separator; commas are accepted only as thousands separators.
- At a real venue, the processing time of the equipment (the latency of digital devices) is added. This tool calculates only the time sound takes to travel through air.
- When the distance is hard to measure, or when you tune how the sound is heard, check with measurements or by listening.
- To relate sound to wavelength and frequency, see the Sound Wavelength Calculator. For a tempo-based delay in milliseconds, see the BPM Delay Calculator.
Frequently asked questions
How many meters is 1 ms?
About 0.3435 m (about 34 cm, or 1.13 ft) at 20 °C. Per meter, that is about 2.91 ms.
Does the delay time change with temperature?
Yes. Sound travels faster in warmer air, so the delay is shorter. 10 m takes about 29.11 ms at 20 °C and about 30.17 ms at 0 °C.
How is a distance in feet calculated?
With 1 ft = 0.3048 m, the distance is converted to meters first. 10 ft is 3.048 m, which takes about 8.87 ms at 20 °C.
How accurate is the speed-of-sound formula?
Between −20 °C and 40 °C it differs from a more exact formula by about 0.2% or less. Humidity, pressure and wind are not considered, so the real speed can differ a little.