There is more than one type of Nautical Mile
There are a few different types of Nautical Mile. On this site we have conversions for US Nautical miles, UK Nautical miles and International Nautical miles. Please either select the appropriate unit on the selection above of click the required unit in the links below:
What is a nautical mile?
A nautical mile is the unit of distance at sea and in the air, and is exactly 1,852 meters. It began as one minute of latitude along any meridian, which varies slightly because the Earth is not a perfect sphere, so a fixed length was agreed internationally.
Latitude is the reason for the length: a degree has 60 minutes, so a nautical mile is a sixtieth of a degree and 21,600 of them go round the Earth. That makes the latitude scale on a chart a distance scale too. Territorial waters extend up to 12 nautical miles from a coast.
What is a US league?
A US league is three miles or 15,840 feet. The word comes from the Late Latin leuca, a Gaulish measure traditionally taken as an hour's walk.
The league was used for the distance between towns and for a ship's run at sea. The mile and the kilometer replaced it, and it now mostly turns up in older books. A US league of three miles is about 4.83km.