A nautical mile is a unit of measurement typically used in marine, air, and space navigation. It does not have an agreed upon symbol; some of the symbols used are M, NM, nmi, and nm. A nautical mile is slightly longer than a land mile.
1 nautical mile = 1.1508 miles
1 nautical mile = 1,852 meters
Nautical mile converter
Why are nautical miles used?
Navigating the sea (or air/space) is different from navigating land, for many reasons. One such reason is that unlike land, things like the landscape, physical landmarks, and other easily distinguishable features cannot be used on sea. One point on the sea looks very much like most every other point, making it difficult to use land measurements while navigating the sea. The use of measurements such as nautical miles and knots allow us to better navigate the sea since their measurement is constant following lines of longitude, allowing the creation of charts that graphically represent the Earth.
What are nautical miles?
Nautical miles are based on the circumference of the earth. Imagine cutting the Earth in half and looking at the circle formed by the equator. Since the equator is a circle, it can be divided up into 360°. Each degree is equivalent to 60 minutes, and each minute of latitude is equal to 1 nautical mile, or one minute of Earth's arc. Therefore:
60 nautical miles = 1° of latitude
Refer to the latitude page for more information. Briefly, latitude indicates the north-south position of a point in the geographic coordinate system. It is measured in terms of degrees or minutes and seconds.
1° = 60 minutes = 3600 seconds = 60 nautical miles
What are knots?
Knots (kn) are a unit of speed derived from nautical miles.
1 knot = 1 nautical mile per hour
This means that a ship that is traveling at 1 knot along a line of longitude travels 1° of latitude in 60 minutes. Below are the relationships between knots and other commonly used measurements of speed.
1 knot = 1.852 kilometers per hour
1 knot = 1.151 miles per hour