Convert speed units — km/h, mph, m/s, knots, Mach.
| Unit | Name | Value |
|---|---|---|
| m/s | Meter per Second | 340.29 |
| km/h | Kilometer per Hour | 1225.043 |
| mph | Mile per Hour | 761.20705 |
| ft/s | Foot per Second | 1116.437 |
| kn | Knot | 661.47141 |
Common mach values converted to knot — factor: 1 mach = 661.5 kn
| Mach (mach) | Knot (kn) | Context |
|---|---|---|
| 0.1 mach | 66.15 kn | Slow aircraft |
| 0.3 mach | 198.4 kn | Small plane |
| 0.5 mach | 330.7 kn | Turboprop |
| 0.75 mach | 496.1 kn | Fast prop |
| 0.85 mach | 562.3 kn | Airliner cruise |
| 0.9 mach | 595.3 kn | Fast airliner |
| 1 mach | 661.5 kn | Speed of sound |
| 1.5 mach | 992.2 kn | Supersonic |
| 2 mach | 1,323 kn | Concorde speed |
| 2.5 mach | 1,654 kn | Fast supersonic |
| 3 mach | 1,984 kn | SR-71 fraction |
| 5 mach | 3,307 kn | Hypersonic |
| 10 mach | 6,615 kn | High hypersonic |
| 20 mach | 1.323e+04 kn | Low orbit |
| 25 mach | 1.654e+04 kn | Space shuttle entry |
Converting mach to knot is essential for drivers, pilots, engineers, and scientists working across different measurement systems. Road speed limits, aviation airspeed, nautical navigation, and physics calculations each use different speed units, making quick and accurate conversion a practical everyday skill.
Key reference points: 5 mach = 3307 kn and 10 mach = 6615 kn. At higher speeds, 100 mach = 6.615e+04 kn. For reverse conversion, multiply kn values by 0.001512 to get back to mach.
All conversions use the internationally recognized factor of exactly 1 mach = 661.5 kn. Calculations are performed in IEEE 754 double-precision floating point, giving accuracy to at least 8 significant figures — more than sufficient for any practical application.
Formula: Knot = Mach × 661.49085
Multiply any mach value by 661.49085 to get knot. One mach equals 661.49085 kn.
Reverse: Mach = Knot × 0.0015117367
1 mach = 661.49085 kn. Memorize this for instant mental estimates.
Use 661.4909 as a quick mental multiplier.
To verify: multiply your result by 0.0015117367 to recover the original mach value.
Designs supersonic and hypersonic aircraft for specific Mach regimes.
Reports aircraft performance and structural limits in Mach number.
Evaluates missile and aircraft performance using Mach speed ratings.
Calculates re-entry heating and trajectory at high Mach numbers.
Reports fighter jet and experimental aircraft speeds in Mach.
Teaches compressible flow and shock wave theory using Mach numbers.
Mach number was named after Austrian physicist Ernst Mach (1838-1916), who studied the properties of supersonic flow. It represents the ratio of an object's speed to the local speed of sound.
Mach is used in aviation and aerospace to describe speeds relative to sound: Mach 1 is the sound barrier (~340 m/s at sea level), Mach 2 is twice that. Commercial aircraft cruise at Mach 0.85, while fighter jets reach Mach 2+.
Interesting fact: The SR-71 Blackbird held the air speed record at Mach 3.3 (3,530 km/h). The Space Shuttle re-entered the atmosphere at Mach 25, and the Parker Solar Probe reached Mach 163.
The knot is a unit of speed equal to one nautical mile per hour, approximately 1.852 km/h or 0.514 m/s. Its name comes from the historical practice of measuring ship speed by counting knots on a rope thrown overboard.
Knots are the international standard for maritime and aviation speed. All commercial aircraft, warships, and weather forecasts use knots. Air traffic control worldwide communicates in knots and feet.
Interesting fact: The cruising speed of a Boeing 747 is about 490 knots (907 km/h). Ocean currents are typically 0.5-1 knot, while Category 5 hurricanes sustain winds above 137 knots.