Kilometer per hour to Mach number Conversion Calculator: Free Online Tool
Convert kilometers per hour to Mach numbers with our free online speed converter.
Kilometer per hour to Mach number Calculator
How to Use the Calculator:
- Enter the value you want to convert in the 'From' field (Kilometer per hour).
- 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 Kilometer per hour to Mach number
Converting Kilometer per hour to Mach number involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Kilometer per hour = 0.000809848 Mach numbersExample Calculation:
Convert 60 kilometers per hour: 60 × 0.000809848 = 0.0485909 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 Kilometer per hour and a Mach number?
Kilometers per hour (km/h or kph) is a unit of speed expressing the number of kilometers traveled in one hour.
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 Kilometer per hour is part of the metric (SI) system, primarily used globally in science and trade. The Mach number belongs to the imperial/US customary system.
History of the Kilometer per hour and Mach number
Kilometers per hour became a common unit of speed with the widespread adoption of the metric system for distance (kilometer) and the standard use of hours for time measurement, particularly following the advent of automobiles and trains where measuring such speeds became practical and necessary.
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 kilometers per hour and Mach numbers
Explore the typical applications for both Kilometer per hour (metric) and Mach number (imperial/US) to understand their common contexts.
Common Uses for kilometers per hour
- Road Traffic: The most common unit for speed limits and vehicle speeds (speedometers) worldwide, except in countries like the US and UK.
- Meteorology: Often used in public weather forecasts to report wind speeds, especially in metric countries.
- Navigation: Used alongside other units like knots in some aviation and maritime contexts, although less common than knots for primary navigation.
- Sports: Sometimes used to describe speeds in cycling, skiing, or running over longer distances.
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 Kilometer per hour (km/h)
Where is km/h primarily used?
Kilometers per hour is the standard unit for road speed in most countries around the world that use the metric system.
Is km/h an SI unit?
While it uses SI units (kilometer and hour derived from second), the official SI unit for speed is meters per second (m/s). However, km/h is accepted for use with SI.
How do you convert km/h to mph?
To approximate, divide the speed in km/h by 1.609. So, 100 km/h is roughly 62 mph. (1 km/h ≈ 0.621371 mph).
How do you convert km/h to m/s?
Divide the speed in km/h by 3.6. So, 100 km/h is approximately 27.78 m/s.
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: Kilometer per hour to Mach number
| Kilometer per hour (km/h) | Mach number (Mach) |
|---|---|
| 1 | 0.001 |
| 5 | 0.004 |
| 10 | 0.008 |
| 25 | 0.02 |
| 50 | 0.041 |
| 100 | 0.081 |
| 500 | 0.405 |
| 1,000 | 0.81 |
All Speed Conversions
Conversion Formula
1 km/h = 0.00081 Mach
Where 1 Kilometer per hour (km/h) equals the calculated value in Mach numbers (Mach).