Miles to Nautical Miles Converter

How many miles are in a nautical mile?

A nautical mile is exactly 1,852 meters. A statute mile, the ordinary land mile, is exactly 1,609.344 meters. The ratio of the two is 1,852 ÷ 1,609.344 = 1.150779, so one nautical mile is about 1.15 land miles, or 6,076.1 feet against 5,280.

nautical miles = statute miles ÷ 1.150779448Equivalent to statute miles × 0.868976. To convert nautical miles to statute miles, multiply by 1.150779448.

Because both lengths are defined exactly in meters, the factor is a fixed ratio rather than a measured quantity. The converter uses 1.150779448, which reproduces the exact ratio to nine decimal places.

Why there are two kinds of mile

The statute mile grew out of the Roman thousand-pace mille passus and was fixed at 5,280 feet in England. It is the mile on road signs in the United States and the United Kingdom.

The nautical mile comes from the sea. It was originally one minute of latitude, a sixtieth of a degree along a meridian, so navigators can read distance straight off the latitude scale of a chart. Ships, aircraft and weather services therefore work in nautical miles, and a speed of one nautical mile per hour is a knot. Since 1 knot equals 1.150779 mph, a boat doing 25 mph is making about 21.7 knots.

Mixed usage is common. US weather reports give visibility in statute miles while airspeeds are in knots, so pilots convert between the two all the time.

How to convert miles to nautical miles

1. Enter the distance in statute miles in the first box.
2. The distance in nautical miles appears in the second box as you type.
3. To convert back, multiply nautical miles by 1.150779448.

Example 1. A flight covers 120 statute miles. 120 ÷ 1.150779448 = 104.277149 nautical miles.

Example 2. A boat does 25 mph. The same conversion turns it into 25 ÷ 1.150779448 = 21.724406 knots.

Example 3. A stretch of coastline is 500 miles long, which is 434.488121 nautical miles.

For a quick estimate, multiply miles by 0.87. The result is about 13% smaller than the mileage because the nautical mile is the longer unit.

Miles to nautical miles conversion table

Common mistakes

• Multiplying instead of dividing. A nautical mile is longer, so a distance in nautical miles is always the smaller number.
• Saying knots per hour. A knot is already a nautical mile per hour, so there is no further "per hour".
• Treating the two miles as equal. Reading 500 statute miles as 500 nautical miles overstates the distance by about 65 nautical miles, enough to matter for fuel and arrival times.

To reverse the calculation, use the nautical miles to land miles converter. For metric distances see the kilometers to nautical miles converter.