Statute Miles vs Nautical Miles Definition On the ocean, distances are calculated slightly differently than on land, hence Nautical phrases are applied as opposed to land or Statute terminology. Nautical Mile (nmi): A unit of distance used in navigation and based on the length of one minute of arc taken along a great circle. This is also sometimes referred to as the International Nautical Mile or an International Air Mile. Please Note the following: Because the Earth is not a perfect sphere, various values have been assigned to the nautical mile. The value 1852 meters (6076.1 ft.) has been adopted internationally. The nautical mile is frequently confused with the geographical mile, which is equal to 1 min of arc on the Earth's equator (6087.15 ft.). Statute mile: A unit of distance equal to 1.609 km (0.869 nmi, 5280 ft.). Comments So the following approximations apply: 1nautical mile = 1.15 statute miles 1 statute mile = 1.6 kilometres From all this, we can state that a knot is a unit of speed one nautical mile per hour, which is approximately 1.15 land or statute miles per hour.