Convert between mph, kph, m/s, knots, and ft/s instantly.
Speed measures how fast an object is moving relative to a reference point, expressed as distance traveled per unit of time. Different fields and regions use different speed units: miles per hour (mph) is standard for road travel in the United States and United Kingdom; kilometers per hour (kph) is used in most of the rest of the world; meters per second (m/s) is the scientific standard; knots are used in aviation and maritime navigation; and feet per second (ft/s) appears in engineering and ballistics. This converter handles all five units with real-time results.
Miles per hour is the standard speed unit for road travel in the United States, the United Kingdom, and a handful of other countries. Highway speed limits in the US typically range from 55 to 75 mph, with some rural interstate highways in states like Texas and Montana allowing 80 to 85 mph. A typical city speed limit is 25 to 35 mph. The unit derives from the statute mile (5,280 feet) and is deeply ingrained in American and British driving culture, road signage, and automotive design.
Kilometers per hour is the most widely used speed unit globally, standard in virtually every country outside the US and UK for road travel. Highway speed limits commonly range from 100 to 130 kph (approximately 62 to 81 mph). Germany's autobahn is famous for sections with no speed limit, where some drivers exceed 200 kph. The metric system's simplicity makes kph easy to work with: driving 100 km at 100 kph takes exactly one hour, and distances on road signs relate directly to travel time at the posted speed.
Meters per second is the SI (International System of Units) standard for speed. It is used in physics, engineering, weather reporting (for wind speed in many countries), and scientific research. The speed of light is defined as exactly 299,792,458 m/s. The speed of sound at sea level is approximately 343 m/s. Converting from kph to m/s is straightforward: divide by 3.6. For example, 100 kph equals 27.78 m/s. This unit provides a direct and intuitive relationship between distance in meters and time in seconds.
A knot equals one nautical mile per hour, approximately 1.852 kph or 1.151 mph. Knots are the standard speed unit in aviation and maritime navigation worldwide. The term dates back to the 17th century when sailors measured speed by dropping a log attached to a rope with evenly spaced knots into the water and counting how many knots passed through their hands in a fixed time period. Nautical miles are based on the geometry of the Earth -- one nautical mile equals one minute of latitude -- making them invaluable for navigation calculations.
| Description | mph | kph | m/s | knots |
|---|---|---|---|---|
| Walking pace | 3.1 | 5.0 | 1.4 | 2.7 |
| Cycling (casual) | 12 | 19 | 5.4 | 10.4 |
| City driving | 30 | 48 | 13.4 | 26.1 |
| Highway driving | 65 | 105 | 29.1 | 56.5 |
| Commercial aircraft | 575 | 926 | 257 | 500 |
| Speed of sound | 767 | 1,235 | 343 | 667 |
The key relationships between speed units are: 1 mph = 1.60934 kph = 0.44704 m/s = 0.86898 knots = 1.46667 ft/s. From these base conversions, you can derive any cross-conversion. For quick mental math: mph to kph, multiply by 1.6; kph to mph, multiply by 0.6; m/s to kph, multiply by 3.6. These approximations are accurate enough for most everyday purposes.
Multiply miles per hour by 1.60934. For example, 60 mph equals approximately 96.56 kph. For a quick estimate, multiply by 1.6.
Multiply kph by 0.62137. For example, 100 kph equals approximately 62.14 mph.
A knot equals one nautical mile per hour (approximately 1.852 kph or 1.151 mph). It is standard in aviation and maritime navigation.
At sea level in dry air at 20 C: approximately 343 m/s, 1,235 kph, 767 mph, 1,126 ft/s, or 667 knots (Mach 1).
Knots are based on nautical miles, which relate directly to Earth's geometry (one nautical mile = one minute of latitude), making navigation calculations simpler on charts.