Converting speed units
Speed conversions run through a base unit — here, meters per second. Each unit has a fixed value in m/s (km/h is 0.2778 m/s, mph is 0.4470 m/s, a knot is 0.5144 m/s), so the value is expressed in m/s and divided by the target unit. That keeps every conversion exact.
km/h and mph, side by side
The most common need is switching a car's speed between kilometers and miles per hour: 100 km/h is about 62 mph, and 60 mph is about 97 km/h. Knots — nautical miles per hour — appear in aviation and sailing, where one knot is about 1.15 mph.
Where each unit is used
Metric countries post limits in km/h; the US and UK use mph. Meters per second is the scientific standard, and feet per second shows up in ballistics and engineering. Picking the two units removes the mental math.
Frequently asked questions
What is 100 km/h in mph?
About 62.1 mph. Multiply km/h by roughly 0.621 to get mph.
How fast is one knot?
One knot is one nautical mile per hour, about 1.852 km/h or 1.15 mph.
How do I convert km/h to mph?
Divide by 1.609 (1 mph = 1.609 km/h). 100 km/h is about 62 mph.
How do I convert m/s to km/h?
Multiply by 3.6. So 10 m/s is 36 km/h.
What is a knot?
One knot is 1.852 km/h — one nautical mile per hour, used at sea and in aviation.