Mach Number to Speed Converter Formula

Understand the math behind the mach number to speed converter. Each variable explained with a worked example.

Use the Mach Number to Speed Converter

Formulas Used

Miles per Hour

mph = mach * 767.269

Kilometers per Hour

kmh = mach * 1234.8

Meters per Second

ms = mach * 343

Variables

VariableDescriptionDefault
machMach Number(M)1

How It Works

How to Convert Mach Number to Speed

Formula

Speed (mph) = Mach × 767.269

Speed (km/h) = Mach × 1234.8

Mach 1 is the speed of sound at sea level and 15 degrees Celsius, approximately 343 meters per second (767.269 mph or 1234.8 km/h). Actual speed of sound varies with temperature and altitude.

Worked Example

Convert Mach 2 to mph and km/h.

mach = 2
  1. 01mph = 2 × 767.269 = 1534.54 mph
  2. 02km/h = 2 × 1234.8 = 2469.60 km/h
  3. 03m/s = 2 × 343 = 686.00 m/s

Frequently Asked Questions

What is Mach 1?

Mach 1 is the speed of sound, approximately 767 mph (1235 km/h) at sea level and 15 degrees Celsius.

Does the speed of sound change with altitude?

Yes, the speed of sound decreases with altitude because temperature drops. At 35,000 ft, Mach 1 is roughly 660 mph.

What is supersonic speed?

Any speed above Mach 1 is supersonic. Speeds above Mach 5 are called hypersonic.

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