Convert speeds | km/h mph Knot

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User Guide

The units for speed are generally represented in distance per time interval. The international units used for distance and time are meters and seconds, which means meters per second (m/s) is the basic unit for speed in the international unit system SI (Système international d'unités). However, Anglo-American or nautical systems use non-metric units such as mile, nautical mile, yard or foot for distances, and therefore these units are used instead of metric units to represent speed. Additionally, other units for speed are used in sports (e.g. km/min) or in technology/science (e.g. speed of light, speed of sound).

Enter the speed to be converted and specify from and to which you want it to be converted. The speed converter provides standard metrics, Anglo-American, nautical and astronomical measures of speed are commonly used for calculation. Additional information on different speed units can be found by clicking on the question mark symbol on the calculator.

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Metric units of speed

The metric system is the unit system using the meter as the basic unit to measure total distance and seconds per time, therefore the basic unit for speed is meters per second (m/s). Some of the speed units are shown below:

Kilometers per hour (km/h)

Kilometers per hour is used as a standard unit in transportation, therefore it is used in traffic or to measure the travel speed of vehicles. This unit is defined as follows: An object moving at 1 "km/h" per hour will cover one kilometer. "km/h" is approved to use in the international system of units (SI).

Kilometers per second (km/s)

Kilometer per second is part of the metric system and it is derived from the standard unit of speed, meter per second (m/s). This unit is defined as follows: An object moving at "1 km/s" per second will cover one kilometer. "km/s" is approved to use in the international system of units (SI).

Meters per minute (m/min)

Meters per minute is defined as follows: An object moving at 1 "m/min" per minute will cover a distance of one meter. "m/min" is approved to use in the international system of units (SI).

Meters per second (m/s)

Meters per second is a basic unit for speed in the International System of Units (SI) and other metric systems. Definition: An object moving at 1 "m/s" per second will cover a distance of one meter. Therefore, both meter and second are the international base units for distance and time. All other speed units in the metric system are derived based on meters per second (e.g. km/h, mm/s).

Millimeter per second (mm/s)

Millimeters per second (mm/s) belongs to the metric system and also derived from the basic unit meter per second (m/s). Definition: An object moving at "1 mm/s" per second covers a distance of one millimeter. "mm/s" is approved to use in the international system of units (SI).

Micrometer per second (μm/s)

Micrometer per second (μm/s) belongs to the metric system and is derived from the basic unit meter per second (m/s). This unit is defined as follows: An object moving at 1 "μm/s" per second covers a distance of one micrometer. One micrometer corresponds to a thousandth millimeter. "μm/s" belongs to the international system of units (SI).

Other metric units

There are many other speed units in the SI system, which represent a fraction or multiple of a meter or a second. This is done by using unit prefixes, like those used in the previous examples. For example, multiples of the meter are kilometers, megameters, hectometers, etc. Fractions of the meter are millimeters, micrometers, nanometers, picometers, etc. Fractions of seconds are displayed in the same way. For example, multiples of seconds are represented in minutes, hours, years. This enables to display even minimal speeds like a micrometer per year in a practical way.

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Anglo-American speed units

The Anglo-American units of speed are not the same as metric units, such as miles, yards or feet, based on time. They are not part of the international system of units and are not SI compatible.

Miles per hour (mph)

The length unit "mile" is commonly used in the Anglo-American countries, where speeds are represented in miles (instead of kilometers) per time unit. The units are defined as follows: An object moving at 1 "mph" per hour will cover a distance of one mile. Therefore, 1 mile is equivalent to 1.609344 kilometers.

Miles per second

Definition: An object moving at 1 "mile per second" covers a one-mile distance.

Yards per hour

The unit is defined as follows: An object moving at 1 "yard per hour" per hour will cover a distance of one yard. Therefore, 1 yard is equivalent to 0.9144 meters (3 feet).

Yards per second

The length unit "yard" is commonly used in Anglo-American countries. For example, speeds are represented by yard per unit of time. Definition: An object moving at 1 "yard per second" per second will cover a distance of one yard. Therefore, 1 yard is equivalent to 0.9144 meters (3 feet).

Feet per minute (ft/min)

The definition of " feet per minute" is as follows: An object moving at 1 "feet per minute" for one minute will cover a distance of one feet. Therefore, 1 feet is equivalent to 30.48 centimeters.

Feet per second

The unit of length in feet is also very common in the Anglo-American countries, therefore speeds are also represented with feet per unit of time. It is defined as follows: An object moving at 1 " feet per second" for one second covers a distance of one feet. Therefore, 1 feet is equivalent to 30.48 centimeters.

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Nautical speed units

Some other measurement units are traditionally used in maritime and aviation. For speed we have mainly:

Knot (kn)

Definition: An object that moves with a knot for one hour will cover a distance of one nautical mile. Therefore 1 nautical mile is equivalent to 1,852 meters. A knot refers to the speed of one nautical mile per hour. The following rule is an easy way to remember when converting knots into km/h: " Multiply by two, and minus 10%". For example, a ship travelling at 20 knots will have a speed around 40-4=36 km/h (exactly 37.04 km/h).

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Speed units used in sports

In sports, speed is commonly measured in time per distance (instead of distance per time), for this reason, the following units are be mentioned here:

Minutes per kilometer (min/km)

For example, the running speed is measured in minutes per kilometer. As a result, a world-class marathon male athletes have an average speed of about 3 min/km during the race.

Minutes per mile (min/mile)

In the Anglo-American countries, the average speed of physical activities is represented in terms of time per distance, similar to the rest of the world. However, here the distance is given in miles instead of kilometers. For example, athletes measure their running speed in minutes per mile.

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Speed units used in other areas

In science and technology, the following two units are mainly used:

Speed of light

Definition: If an object moves at the light speed for one second, it travels a distance of 299,792.458 km or about 300,000 km. This is the light speed that light travels in a vacuum. This speed is also used to propagate radio signals, which is very important in space travel. For example, a signal from Mars takes about 3 to 20 minutes to reach Earth depending on its actual position.

Speed of sound

Definition: If an object travels at the speed of sound in air at 20 degrees Celsius for one second, it travels a distance of 343 meters per second. Actually, it is equivalent to 1.234,8 km/h. The speed of sound is often illustrated by an example of a thunderstorm: if lightning strikes within 3 seconds of the thunder sound, then the thunderstorm is about 1 kilometer away.