# Mach Number Calculator

By Rahul Dhari
Last updated: Jun 14, 2021

The Mach number calculator returns the Mach number for the given speed. If you wondered how fast an aircraft is flying making those loud noises, this calculator tells you much faster it is than the speed of sound. The calculator will also tell you the meaning of the terms – supersonic and subsonic! Scroll down and read on further to understand what is Mach number and how to calculate Mach number.

## What is Mach number?

Sound travels at different speeds in different medium and at different temperatures. That speed is compared with the speed of an object, say an aircraft or a boat. The ratio of the speed of an object and the speed of sound is known as the Mach number. The Mach number is a dimensionless quantity. Mathematically, the Mach number equation can be written as:

`M = v / c`,

such that `v` is the speed of the object and `c` is the speed of sound.

You can also use the `advanced mode` of the calculator if you know the temperature of air. The speed of sound in air at different temperature, `T` °C is given as:

`c = 331.3 * √(1 + T/273.15)`

## How to calculate Mach number?

To calculate Mach number, follow the steps below:

• Step 1: Set the appropriate units for speed from the list on the right. If you need any help with conversion, you can also use our speed converter.
• Step 2: Enter the speed of the object.
• Step 3: Input the speed of sound.
• Step 4: The Mach number calculator will now tell you what is the Mach number for the given object.

## Example: Using the Mach number calculator

Estimate the Mach number for an aircraft flying at a speed `1,500 km/h`. Given the speed of sound as `343 m/s`.

• Step 1: Set the units or convert both speeds into same units, say m/s. Such that,
`v = 1500 km/h = 416.67 m/s`
• Step 2: Enter the speed of aircraft as `416.67 m/s`.

• Step 3: Enter the speed of sound as `343 m/s`.

• Step 4: The Mach number or Mach speed for the aircraft is:

`M = 416.67 / 343 = 1.21`

Alternatively, you can also estimate the speed of an aircraft using its Mach speed. Such as, if the aircraft is travelling at Mach `3`. What is the speed in m/s?

• Step 1: Enter the Mach number as `3`.

• Step 2: Input the speed of sound as `343 m/s`.

• Step 3: The Mach speed calculator will return the speed of the aircraft as 1,029 m/s. Mathematically that's:

`v = M * c = 343 * 3 = 1029 m/s `

## What are supersonic and subsonic flow? The first aircraft ever to break the sound barrier was a Bell X1 aircraft piloted by Chuck Yeager in the year 1947. The sound barrier is the term used when an aircraft is nearing the speed of sound. The Mach speed calculator returns the Mach number. The Mach number is used to characterize the flow speed and mark them in various categories, such as:

Mach number range
Type of flow
Type of objects
Common examples
< 0.8
Subsonic
Passenger aircraft and Helicopters
Dornier 228, Boeing 747-400, Airbus A330-300
0.8-1.2
Transonic
Military trainers
M346 Master, T45 Goshawk, B-1B Lancer
1.2-5.0
Supersonic
Military aircraft
MiG 21 Fishbed, F 16 Fighting Falcon, Mirage 2000H
5.0-10.0
Hypersonic
Ballistic missiles, experimental vehicles
Bramhos-II, NASA X15
Rahul Dhari
Speed of object
ft/s
Speed of sound
ft/s
Mach number
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