How to Convert Aircraft Speed Between Mach and Knots
For aviation and aerospace applications, there is often a need to switch between Mach number and knots. While knots simply measure velocity, Mach represents aircraft speed as a ratio of the speed of sound under current atmospheric conditions. This guide outlines the basic Mach to knots conversion process.
Understanding Mach Number
As a refresher, the Mach number is calculated as:
Mach Number = Aircraft Velocity / Local Speed of Sound
Since the speed of sound varies by altitude and other factors, reference tables are used to determine the appropriate value for conversions:
| Condition | Speed of Sound |
|---|---|
| Sea Level | 661 knots |
| 30,000 ft altitude | 574 knots |
| 60,000 ft altitude | 512 knots |
So Mach 1 equals 661 knots at sea level, but lower knots at higher altitudes.
Calculating Knots from Mach
To transition from Mach number to knots, you multiply the Mach number by the reference speed of sound value for the flight profile.
For example, an aircraft traveling at Mach 0.82 at 30,000 feet is moving at 0.82 * 574 knots = 470 knots.
The process adjusts for the local speed of sound changes.
Key Takeaways
To summarize the key concepts:
- Mach number is aircraft speed/speed of sound
- The speed of sound varies by altitude, temperature, humidity
- Reference tables provide the speed of sound at set conditions
- Use Mach * reference speed of sound = knots
- Use knots/reference speed of sound = Mach
So with the right speed of sound reference values for the conditions, the Mach number can easily be converted to standard airspeed knots.
Type a value in the Mach field to convert the value to Knots:
Knots:
Mach to Knots Formula
knots=Mach*661.4708
Other Value
.80 mach to knots
529.17664
0.72 mach to knots
476.258976
.74 mach to knots
489.48
.760 mach to knots
502.71
0.78 mach to knots
515.947224
1.09 mach to knots
721.00
.76 mach to knots
502.71
0.1 mach to knots
66.14708
0.35 mach to knots
231.51478
Mach to Knots Table Chart
| Mach | Knots |
| 1 | 661.4708 |
| 2 | 1322.9416 |
| 3 | 1984.4124 |
| 4 | 2645.8832 |
| 5 | 3307.354 |
| 6 | 3968.8248 |
| 7 | 4630.2956 |
| 8 | 5291.7664 |
| 9 | 5953.2372 |
| 10 | 6614.708 |
| 11 | 7276.1788 |
| 12 | 7937.6496 |
| 13 | 8599.1204 |
| 14 | 9260.5912 |
| 15 | 9922.062 |
| 16 | 10583.5328 |
| 17 | 11245.0036 |
| 18 | 11906.4744 |
| 19 | 12567.9452 |
| 20 | 13229.416 |
| 50 | 33073.54 |
| 100 | 66147.08 |
| 500 | 330735.4 |
| 1000 | 661470.8 |
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