Speed Converter
Convert between the speed units used on road signs, in aviation, at sea and in physics — km/h, mph, m/s, knots and ft/s.
1
1 Foot per second = 1 ft/s
About this tool
Different fields settled on different units: road signs use km/h or mph, physics uses m/s because it falls straight out of the SI base units, and aviation and shipping use knots, one nautical mile per hour, because a nautical mile matches one minute of latitude.
The handy conversions are exact: 1 mph is 1.609344 km/h, 1 knot is exactly 1.852 km/h, and dividing km/h by 3.6 gives m/s.
Frequently asked questions
- How do I convert km/h to mph?
- Divide by 1.609344. A rough mental version is to multiply by 0.62, so 100 km/h is about 62 mph.
- How do I convert km/h to m/s?
- Divide by 3.6. So 36 km/h is exactly 10 m/s.
- What is a knot?
- One nautical mile per hour, exactly 1.852 km/h. It is standard in aviation and shipping because a nautical mile equals one minute of latitude.
- How fast is the speed of light in these units?
- Exactly 299,792,458 m/s, which is about 1.079 billion km/h.