Convert Mach (M) to Kilometers per Second (km/s)

0.343

≈ 11/32 km/s

At about 20°C in dry air, Mach 1 is approximately 0.343 kilometers per second. Multiply the Mach number by 0.343; the exact speed varies with air temperature and altitude because Mach is defined relative to the local speed of sound.

Conversion Formula

km/s = M × 0.343

Reverse: M = km/s ÷ 0.343

Quick mental math: Multiply Mach by 0.343 at about 20°C.

Conversion Examples

1 M × 0.343 =
0.343 km/s
1 Mach = 0.343 Kilometers per Second
5 M × 0.343 =
1.715 km/s
5 Mach = 1.715 Kilometers per Second
10 M × 0.343 =
3.43 km/s
10 Mach = 3.43 Kilometers per Second
25 M × 0.343 =
8.575 km/s
25 Mach = 8.575 Kilometers per Second
50 M × 0.343 =
17.15 km/s
50 Mach = 17.15 Kilometers per Second
100 M × 0.343 =
34.3 km/s
100 Mach = 34.3 Kilometers per Second

Mach to Kilometer per Second Table

M =—km/s
Mach (M)Kilometer per Second (km/s)
10.343
20.686
31.029
41.372
51.715
62.058
72.401
82.744
93.087
103.43
113.773
124.116
134.459
144.802
155.145
165.488
175.831
186.174
196.517
206.86

Unit Definitions

What is a Mach (M)?

OtherWorldwide

Mach is a dimensionless ratio of an object’s speed to the local speed of sound.

History

The Mach number is named after physicist Ernst Mach and became a standard measure in aerodynamics and high-speed flight.

Current Use

Mach is used in aviation, aerospace engineering, ballistics and compressible-flow research.

Learn more about Mach

What is a Kilometer per Second (km/s)?

Metric (SI)Worldwide

A kilometer per second is a metric speed equal to 1,000 meters traveled in one second.

History

The unit derives directly from the SI-defined meter and second and is useful for very high speeds.

Current Use

Kilometers per second are used for spacecraft, astronomical motion, meteors and other high-speed phenomena.

Learn more about Kilometer per Second

Frequently Asked Questions

How many kilometers per second is Mach 3?
At about 20°C in dry air, Mach 3 is approximately 1.029 km/s. The calculation is 3 × 0.343 = 1.029. The actual value changes with the local speed of sound.
How fast is Mach 1 in km/s?
Mach 1 is approximately 0.343 km/s in dry air at about 20°C. It is about 0.340 km/s in the International Standard Atmosphere at sea level and roughly 0.295 km/s near typical jet cruising altitude.
Why is Mach not a fixed speed?
Mach is the ratio between an object’s speed and the local speed of sound. The speed of sound changes mainly with temperature and also with the medium, so the corresponding value in km/s changes with conditions.

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