Converting Airspeed: Knots to Mach Number
When working with aircraft speeds, pilots and aerospace engineers need to convert between knots and Mach number. While knots measure simple speed, Mach represents speed relative to the speed of sound. This guide outlines the basic conversions.
Understanding Mach Number
Mach number defines velocity as a ratio of the speed of sound. Specifically:
Mach Number = Aircraft Velocity / Speed of Sound
The speed of sound varies by temperature, altitude, and humidity, but is approximately 761 mph (661 knots) at sea level under average conditions.
As examples, common Mach speeds are:
- Mach 0.82 – 657 mph – Typical cruise speed for a commercial jet
- Mach 2 – 1,535 mph – Typical cruise speed for a supersonic military jet
So Mach 1 represents the speed of sound, with higher Mach faster than sound.
Knot/Mach Conversion Process
To convert Mach number to knots, you need to multiply it by the speed of sound in knots at the flight conditions.
| Condition | Speed of Sound |
|---|---|
| Sea Level | 661 knots |
| 30,000 ft altitude | 574 knots |
| 60,000 ft altitude | 512 knots |
For example, at 30,000 ft, Mach 0.82 x 574 knots = 470 knots.
To convert knots to Mach, divide the knots by the speed of sound reference.
Key Takeaways
The key points for knot/Mach conversions:
- Mach number defines speed as a ratio of the speed of sound
- Speed of sound changes with altitude, temperature, humidity
- Reference tables provide speed of sound at defined conditions
- Convert Mach to knots by multiplying Mach by reference speed of sound
- Convert knots to Mach by dividing knots by the reference speed
So with the right speed of sound reference values, knots and Mach number can be interconverted to analyze aircraft performance.
Type a value in the Knots field to convert the value to Mach:
Mach:
Knots to Mach Formula
Mach=knots/661.4708
Example
300 knots to mach
0.45353475920630204
660 knots to mach
0.9977764702538645
1982 knots to mach
2.996352975822969
240 knots to mach
0.3628278073650416
8000 knots to mach
12.094260245501388
90 knots to mach number
0.13606042776189062
convert 100 knots to mach number
0.15117825306876734
4000 knots to mach
6.047130122750694
700 knots to mach
1.0582477714813714
420 knots to mach
0.6349486628888229
490 knots to mach
0.74077344003696
1742 knots to mach
2.6335251684579273
650 knots to mach
0.9826586449469877
340 knots to mach
0.514006060433809
knots to mach conversion Table Chart
1 knots to mach = 0.00151 mach
10 knots to mach = 0.01512 mach
50 knots to mach = 0.07559 mach
100 knots to mach = 0.15118 mach
200 knots to mach = 0.30236 mach
500 knots to mach = 0.75589 mach
1000 knots to mach = 1.51178 mach
Related Converters
1. MPH to KPH
2. MPH to Knots
3. MPH to Mach
4. KPH to MPH
5. KPH to Knots
6. KPH to Mach
7. Knots to MPH
8. Knots to KPH
9. Knots to Mach
10. Mach to MPH
11. Mach to KPH
12. Mach to Knots