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Knot (speed) facts for kids

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Airspeed Indicator
An airspeed indicator, which shows speed in knots
  • meteorology
  • aviation
  • maritime
Quantity: speed
Symbol: kn
Expressed in: 1 kn =
km/h 1.852
mph 1.15078
m/s 0.514444
ft/s 1.68781

The knot is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h (approximately 1.15078 mph). The ISO standard symbol for the knot is kn. The same symbol is preferred by the Institute of Electrical and Electronics Engineers (IEEE); kt is also common, especially in aviation, where it is the form recommended by the International Civil Aviation Organization (ICAO).

The knot is a non-SI unit. 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 approximately one minute of geographic latitude in one hour.

The speeds of vessels relative to the fluids in which they travel (boat speeds and air speeds) are measured in knots. For consistency, the speeds of navigational fluids (tidal streams, river currents and wind speeds) are also measured in knots.


1 international knot =
nautical mile per hour (by definition),
1852.000 metres per hour (exactly),
0.51444 metres per second (approximately),
1.15078 miles per hour (approximately),
20.25372 inches per second (approximately)
1.68781 feet per second (approximately).

The length of the internationally agreed nautical mile is 1852 m. The US adopted the international definition in 1954, having previously used the US nautical mile (1853.248 m). The UK adopted the international nautical mile definition in 1970, having previously used the UK Admiralty nautical mile (6080 ft or 1853.184 m).

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