A knot is a unit of measurement for speed. If you are traveling at a speed of 1 nautical mile per hour, you are said to be traveling at a speed of 1 knot.
While nautical miles measure distance, knots are the unit of choice when it comes to speed in maritime and aviation contexts. One knot equals 1 nautical mile per hour, or about 1.15 statute miles per hour, neatly tying speed to distance in this unique environment.
The term “knot” harks back to the 17th century, where it found its origin in an innovative seafaring tool known as the “common log.” Sailors measured using this device, a rope knotted with uniformly spaced knots attached to a pie slice-shaped piece of wood, to estimate their ship’s speed. The sailors would lower the wood into the water, letting it float freely behind the vessel for a specific amount of time. Once the time elapsed, typically measured with an hourglass, they would count the knots between the ship and the wooden piece to estimate their speed.
To travel around Earth at the equator, you would have to travel 21,600 nautical miles, 24,857 statute miles or 40,003 kilometers.
Understanding the nuanced differences between a nautical mile, a statute mile and a knot is more than just an interesting tidbit of trivia; it’s a critical component of global navigation, enabling precise and consistent measurements across sea, air and space. The next time you’re out sailing, flying or simply looking at a nautical chart, you’ll appreciate the thoughtful calculations behind these unique measurements.
This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.