What Is Knots (kn)?
A knot is a unit used to measure speed. It is mostly used for ships, boats and airplanes. One knot means moving one nautical mile in one hour.
Because Earth is round and maps at sea and in the air are based on latitude and longitude, knots make it easier to measure how fast something travels across the planet.
Definition
1 knot (1 kn) is defined as a speed of 1 nautical mile per hour.
In other common speed units this is about:
- 1 kn ≈ 1.852 km/h (kilometers per hour)
- 1 kn ≈ 1.1508 mph (miles per hour)
- 1 kn ≈ 0.514 m/s (meters per second)
So if a ship travels at 10 knots, it goes about 18.52 kilometers every hour.
History / Origin
The word knot comes from an old way sailors measured speed before modern tools existed.
Sailors used a rope with many knots tied in it and a small wooden board at the end. They threw the board into the water and let the rope run out for a fixed time using a sand timer. Then they counted how many knots passed through their hands. The number of knots that passed in that time told them their speed. From this method the name knot became the name of the speed unit.
This simple tool was called a log line, and it was used on sailing ships for many hundreds of years.
Symbol & Abbreviation
The most common symbol for knots is:
- kn for both singular and plural, for example 1 kn, 12 kn
You may also sometimes see:
- kt or kts in some books or on older instruments
In writing, people usually say:
- 1 knot for the singular
- 5 knots for the plural
Current Use Around the World
Knots are used worldwide anywhere people travel or measure speed over water or through the air.
Main uses today:
- Shipping and boating All kinds of vessels, from large cargo ships to small sailing boats, show speed in knots.
- Aviation Airplanes use knots for airspeed and ground speed. Air traffic control also talks to pilots using knots.
- Weather reports Wind speed over oceans and at high altitude is often given in knots, especially for storms and hurricanes.
- Naval forces Military ships and aircraft worldwide use knots.
Knots are helpful because nautical miles are linked to Earths latitude and longitude. This makes it easier to plan routes and read maps over long distances.
Example Conversions
These examples show how knots compare to kilometers per hour and miles per hour.
From knots to kilometers per hour (km/h)
- 5 kn × 1.852 ≈ 9.26 km/h
- 10 kn × 1.852 ≈ 18.52 km/h
- 20 kn × 1.852 ≈ 37.04 km/h
- 50 kn × 1.852 ≈ 92.6 km/h
From knots to miles per hour (mph)
- 5 kn × 1.1508 ≈ 5.75 mph
- 10 kn × 1.1508 ≈ 11.51 mph
- 20 kn × 1.1508 ≈ 23.02 mph
- 60 kn × 1.1508 ≈ 69.05 mph
From kilometers per hour (km/h) to knots (divide by 1.852)
- 10 km/h ÷ 1.852 ≈ 5.4 kn
- 50 km/h ÷ 1.852 ≈ 27.0 kn
- 100 km/h ÷ 1.852 ≈ 54.0 kn
From miles per hour (mph) to knots (divide by 1.1508)
- 10 mph ÷ 1.1508 ≈ 8.7 kn
- 30 mph ÷ 1.1508 ≈ 26.1 kn
- 60 mph ÷ 1.1508 ≈ 52.1 kn
Related Units
Knots are connected to several other units of speed and distance.
- Nautical mile (NM) The distance unit linked to knots. 1 knot is 1 nautical mile per hour.
- Kilometer per hour (km/h) Common speed unit on roads and in most countries.
- Mile per hour (mph) Common speed unit on roads in the United States and some other places.
- Meter per second (m/s) Speed unit used in science and in the SI system.
Relationships:
- 1 kn ≈ 1.852 km/h
- 1 kn ≈ 1.1508 mph
- 1 kn ≈ 0.514 m/s
- 1 nautical mile ≈ 1.852 kilometers
FAQs
What is a knot in simple words?
A knot is a way to measure how fast something moves over water or through the air. One knot means traveling one nautical mile in one hour.
Why do ships and planes use knots instead of km/h or mph?
Ships and planes travel using maps based on Earths latitude and longitude. Nautical miles and knots match these maps, so they make navigation and route planning easier and safer.
Is a knot faster than a mile per hour?
Yes. One knot is about 1.1508 miles per hour. So if something moves at 10 knots, it is going a little faster than 10 mph, about 11.5 mph.
Is knot an SI unit?
No. The SI unit for speed is meters per second. Knot is a special unit used mainly in navigation for ships and aircraft.
How many knots is 100 km/h?
To convert 100 km/h to knots, divide by 1.852. So 100 km/h is about 54 knots.
Can knots be used on land?
They can be used anywhere, but they are not common on land. On roads people usually use km/h or mph. Knots are mostly kept for sea and air travel.
How many knots is a strong wind?
Weather reports over the sea often use knots. For example, 20 to 33 knots is a fresh to strong breeze, and 34 knots or more can be gale strength.