MPH to Knots Converter

A knot is one nautical mile per hour. The international nautical mile is defined as exactly 1,852 meters, so one knot equals exactly 1.852 km/h. In mph the same speed is 1.15077945 mph, which is a rounded decimal because the statute mile (1,609.344 m) is a different base unit.

Multiply mph by 0.8689762. So 60 mph is 52.14 knots, 100 mph is 86.90 knots, and the highway 65 mph speed limit is 56.48 knots. The exact factor is 1609.344 divided by 1852, which is why the conversion is not a round number.

One knot is one nautical mile per hour. A nautical mile is approximately one minute of latitude along a meridian, so nautical miles and knots fit chart work conveniently. The angular relationship is not exact at every latitude.

US highway speed (60 mph) is about 52 knots. A small Cessna cruises around 100 knots (115 mph). A commercial jet cruises at 450-500 knots (518-575 mph). A 10-knot wind is a gentle breeze on the Beaufort scale, 34 knots is a gale, and 64 knots is hurricane force.

From the 17th-century chip log. Sailors trailed a rope behind the ship with knots tied at fixed intervals (47 feet 3 inches) and a wooden chip on the end. They let it run out for 28 seconds (timed with a sandglass) and counted how many knots passed through their hands. The count gave the ship's speed in nautical miles per hour, so the unit took the same name.