Speed Converter

Use this free speed converter to instantly convert between miles per hour, kilometers per hour, meters per second, feet per second, and knots. Enter any value and all units update automatically.

How to use this Speed Converter

Enter a speed value in any field and all other units update automatically. Type a speed in miles per hour to instantly see the equivalent in kilometers per hour, meters per second, feet per second, and knots. Type in any field and all others convert at the same time. This converter is useful for driving speed conversions, weather reports, aviation, and maritime navigation.

Frequently asked questions

Q: How do I convert mph to kph?
A: Multiply miles per hour by 1.609 to get kilometers per hour. For example, 60 mph × 1.609 = 96.56 kph. To go the other direction, divide kph by 1.609 or multiply by 0.621. A quick mental estimate: multiply mph by 1.6 for a close approximation.

Q: What is a knot in speed?
A: A knot is a unit of speed equal to one nautical mile per hour, where one nautical mile equals 1,852 meters or approximately 1.151 statute miles. Knots are the standard speed unit in aviation and maritime navigation worldwide. A ship traveling at 20 knots is moving at approximately 23 miles per hour or 37 kilometers per hour.

Q: How fast is the speed of sound?
A: The speed of sound in dry air at sea level and 20°C is approximately 343 meters per second, 767 miles per hour, or 1,235 kilometers per hour. This is also called Mach 1. Mach numbers express speed as a multiple of the speed of sound — a fighter jet flying at Mach 2 is traveling at approximately 1,534 mph.

Q: What are typical speed limits in different countries?
A: In the United States, highway speed limits typically range from 65 to 80 mph. In Europe, motorway limits are typically 110 to 130 kph. Australia uses kph with highway limits typically at 110 kph. When driving internationally, this converter helps you quickly understand posted speed limits in the local unit.

Q: How do I convert meters per second to miles per hour?
A: Multiply meters per second by 2.237 to get miles per hour. For example, 10 m/s × 2.237 = 22.37 mph. This conversion is commonly needed in physics problems, weather reports where wind speed is reported in m/s, and sports analytics where athlete speeds may be recorded in m/s.