Convert Mach to knots, mph, km/h, or m/s, or find Mach from speed using ISA sea level, altitude, or custom temperature conditions.
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Mach to Kts Formula
The following formula converts a Mach number M to knots at temperature T (Kelvin) using the ideal-gas speed of sound.
\mathrm{kt} = M \cdot \sqrt{\gamma R T}\, /\, 0.514444- γ (dry air) = 1.4
- R (dry air) = 287.052874 J/(kg·K)
- 1 kt = 0.514444 m/s
- ISA sea level: T = 288.15 K → a ≈ 340.294 m/s ≈ 661.479 kt
Mach to Kts Conversion Table
| Mach | Knots (kt) |
|---|---|
| 0.1 | 66.148 |
| 0.2 | 132.296 |
| 0.3 | 198.444 |
| 0.4 | 264.592 |
| 0.5 | 330.739 |
| 0.6 | 396.887 |
| 0.7 | 463.035 |
| 0.8 | 529.183 |
| 0.9 | 595.331 |
| 1.0 | 661.479 |
| 1.1 | 727.627 |
| 1.2 | 793.775 |
| 1.3 | 859.922 |
| 1.4 | 926.070 |
| 1.5 | 992.218 |
| 1.6 | 1058.366 |
| 1.7 | 1124.514 |
| 1.8 | 1190.662 |
| 1.9 | 1256.810 |
| 2.0 | 1322.958 |
| * Values assume ISA sea level (T = 288.15 K), where a ≈ 661.479 kt. | |
How do you convert Mach to knots? Choose a temperature model (e.g., ISA sea level), compute the speed of sound a = √(γRT), then kt = Mach × a (m/s) ÷ 0.514444.
How do you convert knots to Mach? Convert knots to m/s (×0.514444), then Mach = [speed (m/s)] ÷ a where a = √(γRT) at the chosen temperature.
Example Problem
Convert Mach 0.85 to knots at ISA sea level.
Use a ≈ 661.479 kt at T = 288.15 K, then kt = 0.85 × 661.479.
kt ≈ 562.257 kt