Difference Between Mph and Knot (With Table)

Just like we have a unit to measure liquid: Liters, we use another unit as well to calculate the speed of transports, and two of them that are the most common are: Mph and Knot. In many countries, a Kilometer is used to calculate the speed of vehicles, but Mph is also a common unit to measure road vehicles, especially in the United Kingdom and in the United States. Now, Knot is a unit that is not that ordinary for most people as it is used in the process of Marine and Air aviation.

Mph vs Knot

The main difference between the two-vehicle calculating units is that Mph (Miles per hour) is used in measuring the transportation of road vehicles like cars, trucks, etc. Knot, on the other hand, is used in measuring the speed of air and water travelling vehicles like Airplanes, boats—basically anything with air or ocean aviation.

Mph measures the speed of a mile driven in a time of an hour by a road vehicle. Though it was in the use of many major countries of the world such as Canada, Australia, etc., as the unit of measuring speed, now it is mainly used only in the United Kingdom and in the United States. Miles per hour is a Standard unit of measurement that is used to calculate speed.

The Knot is the most common unit to calculate the speed of any air or ocean travel. Though being a very used unit in non-road vehicles, it is yet not included in the Système International d’Unités that is commonly known as the SI unit. It was first discovered by some Dutch sailors as they abandoned the use of ‘heaving the log’, a method that was used to measure the speed of the ship earlier, And started the method of ‘chip log’.

Comparison Table Between Mph and Knot

Parameters of Comparison




A unit that is used to measure the speed of road vehicles.

The unit used to measure the speed of water and air travelling vehicles.

Main use

In transports that are used on the road: Bike, cars, etc.

In Air crafts and water transports.


 18th century

The Mid-1900s


Mp or mi/h

Kn or kt

Other usage

Railway and some light metro systems as well.

In the process of meteorology.

What is Mph?

Mph or miles per hour is the speed that is covered by a motor vehicle in a span of an hour. The name was discovered in Rome. The first use is of measuring 5000 Roman feet by Roman “mille passus” translated into “thousand paces”.

Just as Knot is additionally used as a tool in meteorology in calculating variations in atmospheric activity, mph is also additionally used in the calculation of railway speeds and in some games that include the use of balls, mainly cricket and baseball. A device Speedometer is used to calculate the speed of transports from the early 29th century.

What is Knot?

The knot is a unit of measure to calculate the speed of mainly three branches: Aircraft speed, freight transport, and the process of meteorology. It is supposed to be founded by Dutch sailors who, instead of using the method of “heaving the log”,. A new method came into existence that would require a wood panel (a triangle shape one) attached to a rope, and that rope would have knots tied around it at some distance. The rope was attached to the time measuring device of that time- a sand glass that was half-filled.

The sailors would throw the wood log in the sea and start the boat. The speed would be calculated by the time taken each Knot that was tied at a similar distance went overboard. The person then would be able to count the speed of the boat or the ship measured by the sand glass.

It is equal to one nautical mile (a unit of measurement that is used in the monitoring and controlling of space, air, and sea/ocean.) that is equal to approximately 1.15078 mph.

Main Differences Between Mph and Knot

  1. The measuring of air and boating crafts is done in a Knot. On the other hand, for almost any travelling vehicle, Mph is used.
  2. The knot is used in the process of meteorology as well. It is a very common use. Mph, on the other hand, is not used in the measurement of the process of meteorology.
  3. A unit of Knot is a tiny bit faster than a single unit of Mph.
  4. Mph can also be used in calculating the speed of the ball for some games like cricket, baseball, and Tennis. Knot definitely isn’t used for this purpose.
  5. While Mph is is a common unit of speed included in the Imperial system of the UK and USA, Knot is not. It is not even a SI unit.


Though Knot is not a common unit for measuring speed as Mph, it does play an important role in the vehicles that are not being travelled on roads. Instead, like Mph, We also know the basic story of its origin. They both have other uses as well other than their main and basic usage in vehicles. These are:

For Mph: In the process of calculating speed in railways and also in some lightweight metros, especially in the United Kingdom. For Knot: Study of the current wavelength and in the process of meteorology for weather forecasting.

Mph is especially used in the United States and the United Kingdom as the main unit to measure the speed of a road vehicle in an hour. While Knot is especially used in air and water travel. Despite the fact of their differences, both speed measuring units are very useful in getting the measuring done in their respective means of transport.


  1. https://www.cambridge.org/core/journals/journal-of-navigation/article/future-of-the-knot-as-a-unit-of-speed/D0B21743391ACF510213CDA907324840
  2. https://books.google.co.in/books?id=GA-4AAAAIAAJ&q=mph+unit+invention&dq=mph+unit+invention&hl=en&sa=X&ved=2ahUKEwjI4-GUwoDwAhXEfH0KHUn9A_IQ6AEwAHoECAEQAw