Speed Converter
Convert between mph, km/h, m/s, knots, Mach and more with instant results and high precision. Perfect for automotive, aviation, marine navigation, and physics calculations.
Speed Conversion Calculator
Convert between metric and imperial speed units with high precision
Popular Conversions
Quick Reference
When to Use Each Unit
Speed Conversion Table
Common speed conversions for quick reference
| From | To | Multiply by | Example |
|---|---|---|---|
| km/h | mph | 0.621371 | 100 km/h = 62.1 mph |
| mph | km/h | 1.609344 | 60 mph = 96.6 km/h |
| m/s | km/h | 3.6 | 25 m/s = 90 km/h |
| km/h | m/s | 0.277778 | 72 km/h = 20 m/s |
| Knots | km/h | 1.852 | 100 kn = 185.2 km/h |
| Knots | mph | 1.15078 | 100 kn = 115.1 mph |
| mph | ft/s | 1.46667 | 60 mph = 88 ft/s |
| Mach | km/h | 1235 | Mach 2 = 2470 km/h |
Understanding Speed Measurements
Speed vs. Velocity
Speed is a scalar quantity that measures how fast an object is moving, regardless of direction. Velocity is a vector quantity that includes both speed and direction. In everyday usage, these terms are often used interchangeably, but in physics, the distinction is important.
Common Speed Conversion Formulas
km/h to mph: multiply by 0.621371
m/s to km/h: multiply by 3.6
Knots to km/h: multiply by 1.852
Mach to km/h: multiply by 1235 (at sea level, 20°C)
Practical Applications
Speed conversion is essential for automotive engineering, aviation (flight planning), marine navigation, sports analytics, weather forecasting, and international travel. Different regions use different units, making conversion tools crucial for safety and communication.
Frequently Asked Questions
What is a knot and why is it used in aviation and marine?
A knot is one nautical mile per hour. Since nautical miles are based on the Earth's circumference (1 nautical mile = 1 minute of latitude), knots provide a natural reference for navigation on Earth's surface, making them ideal for aviation and marine use.
How fast is the speed of sound (Mach 1)?
The speed of sound varies with temperature and altitude. At sea level and 20°C (68°F), Mach 1 is approximately 343 m/s, 1,235 km/h, or 767 mph. Aircraft flying faster than this are supersonic.
Why do different countries use different speed units?
Historical development of measurement systems. Most countries use km/h (metric system), while the US, UK, and a few others use mph (imperial system). Aviation uses knots internationally for consistency and navigation purposes.
How accurate should speed measurements be?
For everyday driving, 1 km/h or 1 mph precision is sufficient. Aviation and marine navigation may require higher precision (0.1 knots). Scientific applications might need even greater accuracy depending on the context.