Speed Of Light to Mach Number Conversion

Enter the speed in speed of light below to get the value converted to Mach number.

Results in Mach Number:
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1 c = Mach 874,030.489796

How to Convert Speed Of Light to Mach Number

Speedometers are used in vehicles to measure speed

To convert a speed of light measurement to a Mach measurement, multiply the speed by the conversion ratio. One speed of light is equal to Mach 874,030.489796, so use this simple formula to convert:

Mach number = speed of light × 874,030.489796

The Mach number is equal to the speed in speed of light multiplied by 874,030.489796.

For example, here's how to convert 5 speed of light to Mach number using the formula above.
5 c = (5 × 874,030.489796) = Mach 4,370,152.44898

Speed of light and Mach number are both units used to measure speed. Keep reading to learn more about each unit of measure.

Speed Of Light

The speed of light is equal to exactly 299,792,458 meters per second, or 670,616,629 miles per hour. The definition of the speed of light is actually derived from the most recent 1983 international definition of the meter.[1]

Speed of light can be abbreviated as c; for example, 1 speed of light can be written as 1 c.

Mach Number

Mach, sometimes also referred to as a Mach number, is the ratio of the speed of an object to the speed of sound.[2]

Mach can be abbreviated as M, and is also sometimes abbreviated as Ma. For example, Mach 1 can be written as 1 M or 1 Ma.

Although Mach can be abbreviated M or Ma, the Mach number is typically expressed with the number after the unit name. For example, the expression Mach 3 is preferred rather than 3 Machs or 3 M.

The speed is classified as either subsonic, transonic, supersonic, or hypersonic depending on the Mach number.

Speed classifications for various mach numbers.
Speed Classification Mach Number
Subsonic Mach < 1.0
Transonic Mach = 1.0
Supersonic Mach > 1.0
Hypersonic Mach > 5.0

Speed Of Light to Mach Conversion Table

Speed of light measurements converted to Mach number
Speed Of Light Mach Number
0.00001 c 8.7403 M
0.00002 c 17.48 M
0.00003 c 26.22 M
0.00004 c 34.96 M
0.00005 c 43.7 M
0.00006 c 52.44 M
0.00007 c 61.18 M
0.00008 c 69.92 M
0.00009 c 78.66 M
0.000001 c 0.87403 M
0.00001 c 8.7403 M
0.0001 c 87.4 M
0.001 c 874.03 M
0.01 c 8,740 M
0.1 c 87,403 M
1 c 874,030 M


  1. National Institute of Standards and Technology, SI Redefinition: Meter, https://www.nist.gov/si-redefinition/meter
  2. NASA, Mach Number, https://www.grc.nasa.gov/WWW/BGH/mach.html