Kilometres per hour (km/h) to Knot (kn)
To convert kilometers per hour to knots, multiply by 0.5400. One knot equals 1.852 km/h — exactly one nautical mile per hour. Knots are standard in US aviation, the Coast Guard, and sailing. While everyday American weather reports tend to use miles per hour, marine forecasts and aeronautical charts use knots as the universal standard.
Frequently asked questions
30 km/h × 0.5400 = 16.2 knots. This is equivalent to a moderate breeze — roughly Force 4 on the Beaufort scale — a common speed for recreational sailing conditions.
Knots are based on the nautical mile, which corresponds to one arcminute of latitude. This makes position and distance calculations much simpler in navigation, where coordinates are expressed in degrees and minutes. The FAA, US Navy, and international aviation and maritime organizations all mandate the use of knots.
The National Weather Service issues a gale warning when sustained marine winds of 34–47 knots (63–87 km/h) are forecast. A storm warning is issued for sustained winds of 48–63 knots, and a hurricane warning for sustained winds of 64 knots or higher.
The National Weather Service uses both, depending on the audience. Public weather forecasts for land use miles per hour. Marine forecasts, coastal water forecasts, and aviation weather (METARs, TAFs) use knots, following international standards set by the WMO and ICAO.