Mach ↔ KPH
Convert between Mach number and kilometers per hour. For aviation and supersonic speeds.
kph = Mach × 1234.8 (at sea level)
Quick Reference: common conversions
| From | To |
|---|---|
| Mach 0.5 | 617.4 KPH |
| Mach 0.8 | 987.84 KPH |
| Mach 0.95 | 1,173.1 KPH |
| Mach 1 | 1,234.8 KPH |
| Mach 1.5 | 1,852.2 KPH |
| Mach 2 | 2,469.6 KPH |
| Mach 3 | 3,704.4 KPH |
| Mach 5 | 6,174 KPH |
| Mach 8 | 9,878.4 KPH |
| Mach 10 | 12,348 KPH |
| Mach 20 | 24,696 KPH |
| Mach 30 | 37,044 KPH |
| 1 KPH | Mach 0.0008 |
| 10 KPH | Mach 0.0081 |
| 100 KPH | Mach 0.081 |
Mach number is a speed expressed as a multiple of the speed of sound. This converter uses the speed of sound in dry air at 20 °C at sea level, 343 m/s, so Mach 1 = 1,234.8 km/h (767.3 mph, 666.7 knots). Multiply the Mach number by 1,234.8 to get km/h; divide km/h by 1,234.8 to get Mach.
Mach numbers in km/h, mph and knots
| Mach | km/h | mph | knots | Example |
|---|---|---|---|---|
| Mach 0.5 | 617.4 | 383.6 | 333.4 | Turboprop airliner |
| Mach 0.8 | 987.8 | 613.8 | 533.4 | Jet airliner cruise |
| Mach 0.95 | 1,173.1 | 728.9 | 633.4 | Transonic |
| Mach 1 | 1,234.8 | 767.3 | 666.7 | Speed of sound (sea level, 20 °C) |
| Mach 1.5 | 1,852.2 | 1,150.9 | 1,000.1 | Fighter jet supercruise |
| Mach 2 | 2,469.6 | 1,534.5 | 1,333.5 | Concorde cruise (2.04) |
| Mach 3 | 3,704.4 | 2,301.8 | 2,000.2 | SR-71 Blackbird (3.2+) |
| Mach 5 | 6,174.0 | 3,836.3 | 3,333.7 | Hypersonic threshold |
| Mach 8 | 9,878.4 | 6,138.1 | 5,333.9 | Scramjet test vehicles |
| Mach 10 | 12,348 | 7,672.7 | 6,667.4 | X-43A (9.6) |
| Mach 20 | 24,696 | 15,345.4 | 13,334.8 | Ballistic re-entry |
| Mach 30 | 37,044 | 23,018.1 | 20,002.2 | Close to orbital velocity |
Why Mach 1 is not a fixed speed
The speed of sound depends on air temperature, not pressure. At sea level on a 20 °C day it is 343 m/s (1,234.8 km/h); at 15 °C it is 340 m/s (1,225 km/h); at a typical cruising altitude of 11 km, where the air is about −56 °C, it drops to roughly 295 m/s (1,062 km/h). An aircraft flying Mach 0.85 at altitude is therefore travelling slower in km/h than Mach 0.85 at sea level. Always quote the altitude or temperature alongside a Mach number when precision matters.
Related converters: knots to kph and kph to mph.