Knots are a unique way of measuring speed, used primarily in maritime and aviation settings. While most people are familiar with kilometers per hour or miles per hour, knots have a long history and remain the standard for ships and aircraft.

The term “knot” comes from an old nautical practice. Sailors used a rope with knots tied at regular intervals, called a log line, to measure their ship’s speed. They would throw the rope overboard and let it run out for a set amount of time. By counting the knots that passed, they could estimate how fast the ship was moving. This simple method became the foundation for the speed unit we still use today.

A knot is equal to one nautical mile per hour. Nautical miles are based on the Earth’s geometry, making them ideal for navigation over long distances. Unlike standard miles or kilometers, nautical miles connect directly to latitude and longitude, which is why knots are practical for plotting courses at sea and in the air.

Modern ships and aircraft continue to use knots because they provide consistency and reliability. Shipping routes, flight plans, and navigation charts all rely on this unit, making communication and calculations much easier across international waters and skies. Even wind speeds are often reported in knots, helping pilots and sailors adjust routes and maintain safety.

Typical cruising speeds vary depending on the vessel or aircraft. Passenger ships might travel at 20–25 knots, fast ferries at 30–40 knots, and commercial airliners cruise at 450–500 knots. Military jets, of course, can exceed these speeds, but even supersonic aircraft often still reference knots for navigation.

Knots may have originated centuries ago with simple ropes and logs, but today they remain a crucial tool for safe and accurate travel. Understanding knots gives insight into navigation history, modern shipping, and aviation, connecting past techniques to today’s high-tech world.