Basic Speed Converter
To use this speed/velocity converter, choose two units, then type some value in the box at left (input). The converted result will immediately appear in the output box at right.
Basic Speed Unit Converter 

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Detailed result here

Popular conversions: mph to kph, mph to knots, mph to meters per second, knots to mph, knots to miles per hour, meter per second to miles per hour, meter per second to kilometers per hour.
Converting speed units
Supose we want to convert 70 miles/hour to Km/hour. We know that 1 mile = 1.609344 km.
So, 1 mile/hour = 1.609344 km/hour then,
70 x 1 mile/hour = 70 x 1.609344 km/hour = 112.65408 km/hour.
To convert speed from mile/hour to km/hour just use the formula:
(Speed in mile/hour) = (speed in km/hour) x 1.609344
Supose we want to convert 100 Km/hour to miles/hour. We know that 1 mile = 1.609344 km => 1 Km = 1 / 1.609344 miles = 0.62137119223733 miles.
So, 1 km/hour = 0.62137119223733 mile/hour then,
100 x 1 km/hour = 100 x 0.62137119223733 mile/hour = 62.137119223733 mile/hour.
To convert speed from km/hour to mile/hour just use the formula:
(Speed in km/hour) = (speed in mile/hour) x 0.62137119223733
Speed x velocity
Speed
Speed is a scalar quantity that refers to "how fast an object moves". Scalars are quantities with only magnitude. The direction does not matter. Speed is the rate at which an object covers a given distance. The average speed is defined as the total DISTANCE divided by the total time.
(Average Speed) = (Total DISTANCE) ÷ (Total Time)
Example 1: If a person walked 100 m in a straight line in 2 min, their average speed would be (100 m) ÷ (2 min) = 50 m/min.
If the same person walked 60 m [east] then 40 m [west] in 2 minutes, their average speed would still be (60 + 40) ÷ 2 = 100 ÷ 2 = 50 m/min.
Velocity
Velocity is a vector. Both quantity and direction must be stated. It a car has a velocity of 110km/h north, and a second car has a velocity of 110km/h south, the two cars will have same speed but different velocities. When we evaluate the velocity of an object, we must keep track of direction. The average velocity is defined as the total DISPLACEMENT divided by the total time.
(Average Velocity) = DISPLACEMENT ÷ (Total Time)
Example 2: If the same person of example 1 walked 60 m [east] then 40 m [west] in 2 minutes, their average speed would still be (60 + 40)÷2 = 100÷2 = 50 m/min, but their average velocity would be (60  40) ÷ 2 = 20 ÷ 2 = 10 m/min.