Sailors, pilots and meteorologists still speak in knots — a unit almost no one uses on land, yet indispensable at sea and in the air. This tool converts knots into the more familiar km/h.
A speed unit literally measured by counting knots in a rope
The knot's name describes its own historical measuring method: 16th and 17th-century sailors measured ship speed using a "chip log," a wooden board tied to a rope with evenly spaced knots, thrown overboard and timed with a sandglass — counting how many knots paid out in a fixed time gave the ship's speed directly in "knots." The unit survived the transition from sail to steam to jet propulsion because it's tied to something genuinely useful for navigation: one knot equals one nautical mile per hour, and a nautical mile is defined as one minute of latitude — meaning a ship or aircraft's speed in knots relates directly and conveniently to how fast it's covering degrees of the Earth's surface, which matters enormously for celestial and chart-based navigation.
The conversion
1 knot = 1.852 km/h exactly, since a nautical mile is internationally defined as exactly 1,852 meters. The tool multiplies your knot value by this precise constant — unlike the mile/kilometer conversion, this one has no historical ambiguity because the nautical mile's modern definition was fixed by international agreement in 1929.
Where knots are still the standard, and why
- Maritime navigation — every ship's log, radar display and navigational chart worldwide reports speed in knots, a genuine international standard rather than a regional holdout.
- Aviation — airspeed indicators in virtually all aircraft, from small Cessnas to commercial airliners, are calibrated in knots, alongside altitude in feet, making these two of the few universally metric-resistant aviation units.
- Wind speed forecasting for sailors and pilots — marine and aviation weather forecasts specifically report wind in knots, distinct from the km/h or mph figures used in general public weather reports for the same storm system.
- Hurricane and tropical storm classification — meteorological agencies frequently report a storm's sustained wind speed in knots internally, even when public-facing bulletins convert it to mph or km/h.
Frequently asked questions
Why didn't aviation and shipping switch to km/h like most other industries? Because knots are directly tied to the nautical mile, which is itself tied to degrees of latitude — a genuinely useful property for navigation calculations that km/h doesn't share, giving knots a functional advantage that outweighed pressure toward general metrication.
Is a knot faster or slower than an mph? Slightly faster — 1 knot equals about 1.15078 mph, since a nautical mile (1,852 m) is longer than a statute mile (1,609.344 m).
How is wind speed different from ground speed in knots? They use the identical unit, but wind speed measures air movement while ground speed measures an aircraft or vessel's actual movement over the Earth's surface, which can differ significantly due to headwinds, tailwinds or ocean currents.
Further reading
Wikipedia — Knot (unit) — The chip-log origin of the knot and its exact modern nautical-mile-based definition.