Speed Converter
Convert speed between miles per hour, kilometers per hour, meters per second, and knots.
Frequently Asked Questions
How do I convert mph to km/h?
To convert miles per hour (mph) to kilometers per hour (km/h), multiply by 1.60934. For example, 60 mph equals about 96.56 km/h. This conversion is important for international drivers and travelers since the United States uses mph while most countries use km/h on road signs. A handy rule of thumb is that 100 km/h is roughly 62 mph — useful for quickly interpreting foreign speed limit signs without a calculator.
What is a knot in terms of speed?
A knot is one nautical mile per hour, equal to approximately 1.852 km/h or 1.15078 mph. Knots are used in maritime and aviation navigation because they relate directly to nautical miles, which correspond to degrees of latitude on a globe. This makes navigation calculations simpler. A ship traveling at 20 knots covers about 37 km per hour. Pilots and sailors worldwide use knots regardless of their country's standard unit system.
How fast is the speed of light in common units?
The speed of light is approximately 299,792,458 meters per second, or about 186,282 miles per second. In km/h, that is roughly 1.079 billion km/h. Light travels from the Earth to the Moon in about 1.3 seconds. While these figures are mostly relevant for physics and astronomy, they provide a useful upper reference point when understanding extreme speeds. No physical object with mass can reach or exceed the speed of light according to Einstein's theory of relativity.