Speed Converter

Enter a speed in either field and select the units you want to convert between. The other field updates immediately, and Swap reverses the conversion.

The result also shows the same speed in the other supported units, the conversion factor for the selected pair, and the distance that speed covers in one second and one minute.

To convert kilometres per hour to miles per hour, multiply by approximately 0.621371.

For example, 100 km/h is approximately 62.1371 mph, while 72 km/h is approximately 44.7387 mph.

km/h is sometimes typed as kmh or kmph in searches and informal writing. The standard unit symbol used by this converter is km/h.

To convert miles per hour to kilometres per hour, multiply by exactly 1.609344.

For example, 60 mph equals 96.56064 km/h, 72 mph equals 115.872768 km/h, and 190 mph equals 305.77536 km/h.

One kilometre contains 1,000 metres and one hour contains 3,600 seconds. Therefore 1 km/h equals 1,000 ÷ 3,600 m/s, which simplifies exactly to 5/18 m/s.

So converting km/h to m/s uses × 5/18. The reverse conversion, m/s to km/h, uses × 18/5, which is the same as multiplying by 3.6.

The 5/18 factor does not convert km/h to mph. For km/h to mph, use approximately 0.621371 instead.

One mile per hour equals exactly 0.44704 metres per second.

That makes 60 mph exactly 26.8224 m/s. Converting the other direction uses approximately 2.23694 mph for each metre per second.

One knot means one international nautical mile per hour. The international nautical mile is exactly 1,852 metres, so one knot equals exactly 1.852 km/h.

One knot is approximately 1.15078 mph. Knots are commonly used for marine navigation, aviation, and some wind-speed reporting.

A knot already contains the per-hour relationship, so phrases such as knots per hour are not correct speed units.

One international foot equals exactly 0.3048 metre, so one foot per second equals exactly 0.3048 m/s.

Feet per second is less common for everyday road speeds but still appears in engineering, technical specifications, flow measurements, and some sports data.

A unit conversion tells you the same speed in another unit, but a distance-per-time view can make the number easier to understand.

For example, 190 mph is about 84.94 m/s. At a constant 190 mph, an object would therefore cover about 84.94 metres each second.

The live converter calculates this one-second and one-minute distance automatically from the entered speed.

A kilometre is a unit of distance. A kilometre per hour is a unit of speed.

A value such as 900 km cannot be converted directly to mph because the time taken to cover those 900 kilometres is unknown. To calculate speed, both distance and time are required.

If the intended value is 900 km/h, that speed is approximately 559.2341 mph.

Speed describes how quickly distance is covered and has magnitude only. Velocity includes both magnitude and direction.

This calculator converts non-negative speed magnitudes. It does not calculate vector direction or resultant velocity.

Different fields use different speed units even when they describe the same physical quantity.

Road travel commonly uses km/h or mph, scientific work often uses m/s, and knots are closely associated with navigation.

These examples cover common road-speed, physics, and navigation conversions.

The live converter uses the same underlying factors before formatting the displayed result.

Mach number is the ratio of an object's speed to the local speed of sound.

The speed of sound changes with the medium and physical conditions, including temperature, so Mach 1 does not correspond to one universal mph or km/h value.

For that reason, this converter includes only speed units with fixed unit relationships.

Conversions use the unit relationships before the result is formatted for display. This avoids intentionally rounding through an intermediate unit.

An exact unit factor does not make a measured speed exact. GPS accuracy, radar or sensor calibration, instrument resolution, averaging, wind, and measurement conditions can affect the original reading.