Convert Speed
Convert speed measurements between different units quickly and accurately
Speed Conversion Calculator
Popular Speed Conversions
Quickly convert between the most commonly used speed units.
Understanding Speed Measurements
Speed conversions are essential for various applications, from transportation and sports to scientific research and engineering. Understanding speed conversions ensures accurate and consistent results across different measurement systems and scales.
Common Speed Units
Metric Units
- Meters per Second (m/s)
- Centimeters per Second (cm/s)
- Millimeters per Second (mm/s)
- Kilometers per Hour (km/h)
- Kilometers per Second (km/s)
Imperial & Other Units
- Miles per Hour (mph)
- Feet per Second (ft/s)
- Inches per Second (in/s)
- Knots (kn)
- Mach (M)
Common Applications
| Field | Measurement Types | Typical Uses |
|---|---|---|
| Transportation | Kilometers per Hour, Miles per Hour | Vehicle speed, traffic management |
| Sports | Meters per Second, Kilometers per Hour | Athletic performance, race timing |
| Aviation | Knots, Mach | Aircraft speed, flight planning |
| Scientific Research | Centimeters per Second, Millimeters per Second | Laboratory measurements, material testing |
| Space & Astronomy | Kilometers per Second | Orbital velocities, space missions |
| Engineering | Meters per Second, Inches per Second | Machinery, precision instruments |
| Everyday Use | Kilometers per Hour, Miles per Hour | Walking speed, cycling |
Conversion Tips
- 1 km/h equals approximately 0.621371 mph
- 1 mph equals approximately 1.609344 km/h
- 1 m/s = 100 cm/s = 1000 mm/s
- 1 km/s = 1000 m/s (orbital and escape velocities)
- Remember that 1 knot = 1.15078 miles per hour
- Speed is always a ratio of distance to time
Speed Conversions
| Conversion | Formula/Rule | Quick Answer |
|---|---|---|
| Kilometers per Hour to Miles per Hour | 1 mph = 1.609344 km/h | Divide km/h by 1.609344 |
| Miles per Hour to Kilometers per Hour | 1 km/h = 0.621371 mph | Multiply mph by 1.609344 |
| Meters per Second to Kilometers per Hour | 1 km/h = 0.277778 m/s | Multiply m/s by 3.6 |
| Kilometers per Hour to Meters per Second | 1 m/s = 3.6 km/h | Divide km/h by 3.6 |
| Meters per Second to Centimeters per Second | 1 m/s = 100 cm/s | Multiply m/s by 100 |
| Centimeters per Second to Meters per Second | 1 cm/s = 0.01 m/s | Divide cm/s by 100 |
| Kilometers per Second to Meters per Second | 1 km/s = 1000 m/s | Multiply km/s by 1000 |
| Knots to Miles per Hour | 1 mph = 0.868976 kn | Multiply kn by 1.15078 |
| Miles per Hour to Knots | 1 kn = 1.15078 mph | Divide mph by 1.15078 |
| Mach to Miles per Hour | 1 mph = 0.00130332 M | Multiply M by 767.269 |
| Miles per Hour to Mach | 1 M = 767.269 mph | Divide mph by 767.269 |
Our comprehensive speed conversion tool provides accurate conversions between all major speed units, from scientific measurements to everyday applications. Whether you're working in transportation, sports, engineering, or scientific research, our converter ensures precise speed conversions across all scales.
Speed Conversion Questions
Everything you need to know about speed measurements and conversions
What's the difference between speed and velocity?
Speed is the magnitude of motion (how fast), while velocity includes both speed and direction (how fast and which way). Speed is a scalar quantity measured in units like mph or m/s. Velocity is a vector quantity that changes if either speed or direction changes, even if the other remains constant.
Why do ships and aircraft use knots instead of mph or km/h?
Knots are directly related to navigation on Earth's surface. One knot equals one nautical mile per hour, and one nautical mile equals one minute of latitude (1/60th of a degree). This makes navigation calculations simpler when using charts and coordinates, as distances can be directly measured against latitude lines.
What is Mach number and how does it work?
Mach number is the ratio of an object's speed to the speed of sound in the surrounding medium. Mach 1 is the speed of sound (about 343 m/s or 767 mph at sea level). Mach varies with altitude and temperature since sound speed changes. Supersonic flight begins at Mach 1, hypersonic at Mach 5.
How do I calculate average speed vs instantaneous speed?
Average speed = total distance ÷ total time. For example, 100 km in 2 hours = 50 km/h average. Instantaneous speed is the speed at a specific moment, measured over an infinitely small time interval. Speedometers show instantaneous speed, while trip computers calculate average speed.
Why can't anything go faster than the speed of light?
According to Einstein's special relativity, the speed of light in vacuum (299,792,458 m/s) is the universal speed limit. As objects approach this speed, their mass effectively increases, requiring infinite energy to reach light speed. Only massless particles like photons can travel at light speed.
How accurate are GPS speed measurements?
GPS speed accuracy is typically within 0.1-0.2 mph under good conditions. It calculates speed by measuring position changes over time using satellite signals. Accuracy decreases in tunnels, urban canyons, or with poor satellite visibility. Modern GPS is often more accurate than vehicle speedometers.
What's the fastest speed ever achieved by humans?
The fastest crewed vehicle was Apollo 10 at 39,897 km/h (24,791 mph) during lunar return. The fastest robotic spacecraft is NASA's Parker Solar Probe, which reached over 532,000 km/h (330,000 mph). On Earth, land speed records are around 1,228 km/h (763 mph) for jet-powered vehicles.
How do speed limits work in different countries?
Speed limits vary globally and use different units. Most countries use km/h (kilometers per hour), including Europe, Asia, and Australia. The USA, UK (partially), and a few others use mph (miles per hour). Always check local units when traveling. Highway speeds typically range from 80-130 km/h (50-80 mph) in most countries.
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