Knot to Mach number Conversion Calculator: Free Online Tool
Convert knots to Mach numbers with our free online speed converter.
Knot to Mach number Calculator
How to Use the Calculator:
- Enter the value you want to convert in the 'From' field (Knot).
- The converted value in Mach number will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Speed category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Knot to Mach number
Converting Knot to Mach number involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Knot = 0.00149984 Mach numbersExample Calculation:
Convert 60 knots: 60 × 0.00149984 = 0.0899903 Mach numbers
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
What is a Knot and a Mach number?
The knot (kn) is a unit of speed equal to one nautical mile per hour, which is exactly 1.852 km/h (approximately 1.15078 mph or 0.514 m/s).
The Mach number (M or Ma) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. It is named after Austrian physicist and philosopher Ernst Mach.
Note: The Knot is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Mach number belongs to the imperial/US customary system.
History of the Knot and Mach number
The term knot originates from the 17th century practice of measuring ship speed using a "chip log". This device consisted of a rope with knots tied at uniform intervals (47 feet 3 inches or 14.4018 m), attached to a piece of wood shaped like a sector of a circle. The log was thrown overboard, and sailors counted the number of knots that passed through their hands in a specific time (usually measured by a 28-second sandglass). The number of knots counted in that time directly corresponded to the ship's speed in nautical miles per hour.
The term "Mach number" was proposed by Swiss aeronautical engineer Jakob Ackeret in 1929. It gained prominence during World War II with the development of high-speed aircraft. The sound barrier (Mach 1) was famously broken by Chuck Yeager in 1947.
Common Uses for knots and Mach numbers
Explore the typical applications for both Knot (imperial/US) and Mach number (imperial/US) to understand their common contexts.
Common Uses for knots
- Maritime Navigation: The primary unit for measuring vessel speed in maritime contexts worldwide.
- Aviation: Standard unit for indicating airspeed for aircraft globally.
- Meteorology: Commonly used to report wind speeds, especially in forecasts for marine and aviation purposes.
Common Uses for Mach numbers
- Aerospace: Describing the speed of aircraft and spacecraft relative to the speed of sound (subsonic, transonic, supersonic, hypersonic).
- Fluid Dynamics: Analyzing high-speed flows in wind tunnels, jet engines, and rocket nozzles.
- Ballistics: Characterizing the speed of projectiles.
Frequently Asked Questions
Questions About Knot (kn)
What is a knot based on?
A knot is equal to one nautical mile per hour. A nautical mile is based on the Earth's circumference (one minute of latitude).
Is the knot an SI unit?
No, the knot is not an SI unit, but it is accepted for use with the SI, especially in navigation.
Why are knots used instead of mph or km/h in navigation?
Knots are convenient because one knot is one nautical mile per hour, and a nautical mile directly relates to the lines of latitude and longitude on navigational charts (one nautical mile is approximately one minute of latitude).
How do you convert knots to mph?
Multiply the speed in knots by approximately 1.151. So, 20 knots is about 23 mph.
How do you convert knots to km/h?
Multiply the speed in knots by 1.852. So, 20 knots is exactly 37.04 km/h.
About Mach number (Mach)
What does Mach 1 mean?
Mach 1 represents the speed of sound in the surrounding medium under specific conditions (temperature, pressure, altitude). At standard sea level conditions (15°C and 1 atm), Mach 1 is approximately 343 meters per second (1,235 km/h; 767 mph).
Is the speed of Mach 1 constant?
No, the speed of sound varies primarily with temperature. It decreases at higher altitudes where the air is colder. Therefore, the actual speed corresponding to Mach 1 changes with altitude and atmospheric conditions.
What are the different speed regimes related to Mach number?
- Subsonic: M < 0.8
- Transonic: 0.8 ≤ M < 1.2
- Supersonic: 1.2 ≤ M < 5
- Hypersonic: M ≥ 5
Conversion Table: Knot to Mach number
| Knot (kn) | Mach number (Mach) |
|---|---|
| 1 | 0.002 |
| 5 | 0.008 |
| 10 | 0.015 |
| 25 | 0.038 |
| 50 | 0.075 |
| 100 | 0.15 |
| 500 | 0.75 |
| 1,000 | 1.5 |
All Speed Conversions
Conversion Formula
1 kn = 0.0015 Mach
Where 1 Knot (kn) equals the calculated value in Mach numbers (Mach).