Knot (unit)

Knot (unit)

The knot (pronounced not) is a unit of speed equal to one nautical mile (1.852 km) per hour, approximately 1.151 mph. There is no standard abbreviation but kn is commonly used; kt and NMPH are also seen. The knot is a non-SI unit accepted for use with the International System of Units (SI). Worldwide, the knot is used in meteorology, and in maritime and air navigation—for example, a vessel travelling at 1 knot along a meridian travels one minute of geographic latitude in one hour. Etymologically, the term knot derives from counting the number of knots in the line that unspooled from the reel of a chip log in a specific time.