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Speed of Sound Converters

Convert Mach numbers to and from m/s, km/h, mph, knots and feet per second.

What this tool does

Convert Mach numbers to and from m/s, km/h, mph, knots and feet per second. Type an amount in mach (standard atmosphere, sea level, 15 °C), choose the units, and the tool converts it to kilometers per hour. It offers 6 speed units and also shows the same amount in the others.

Inputs

  • Value: A number.
  • From: Choose one: Mach (standard atmosphere, sea level, 15 °C), Meter per second, Kilometer per hour, Mile per hour, Knot, Foot per second. Starts as Mach (standard atmosphere, sea level, 15 °C).
  • To: Choose one of the same 6 units as "From". Starts as Kilometer per hour.

How to use

  1. Enter the amount you want to convert.
  2. Choose the unit to convert from and the unit to convert to.
  3. Read the result: the converted amount and the same amount in the other units. It appears once every required field has a valid value.

Worked examples

Conversions from mach (standard atmosphere, sea level, 15 °C) to kilometers per hour:

  • 1 Ma ≈ 1,225.0584 km/h
  • 5 Ma ≈ 6,125.292 km/h
  • 10 Ma ≈ 12,250.584 km/h
  • 50 Ma ≈ 61,252.92 km/h
  • 100 Ma ≈ 122,505.84 km/h

Multiply the number of mach (standard atmosphere, sea level, 15 °C) by 1,225.0584 to get kilometers per hour. At least one of these units is not an exact definition, so this factor is a rounded value.

Sources: Mach (standard atmosphere, sea level, 15 °C): ISO 2533:1975 Standard Atmosphere. Kilometer per hour: exact by definition.

Limitations

  • Mach here means the standard-atmosphere sea level value only. At altitude or in warmer or colder air, the same Mach number is a different speed.

FAQs

Q: How fast is the speed of sound?
A: At sea level in the ISO standard atmosphere (15 °C) it is 340.294 m/s, about 1,225.06 km/h or 761.216 mph.
Q: Does the speed of sound change?
A: Yes. It depends mainly on air temperature, so it is lower in cold air, including the cold air found at cruising altitude. This page uses the fixed standard sea level value.
Q: Can I convert a speed to Mach?
A: Yes. Choose a speed unit in the From box and Mach in the To box.

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