# How fast is mark one?

**4 Answers**

Mach 1, the speed of sound, is 737.269 miles (1234.8 km) per hour.

Mach One is equal to the local speed of sound. The speed of sound varies based on the temperature of the air the sound is traveling in, with sound traveling slower in cooler air. Assuming a temperature of 59 degrees Fahrenheit at sea level, the speed of sound is 761.2 miles per hour.

Mach 1 is the speed of sound, which is approximately 760 miles per hour at sea level.

Mach number is a ratio of the speed of a body (aircraft) to the speed of sound in the undisturbed medium through which the body is traveling. It is said that the aircraft is flying at Mach 1 if its speed is equal to the speed of sound in air which is 767.269 miles per hour.