# Speed

Convert Speed units quick and easy, online

## Kilometers per hour

The kilometre per hour (SI symbol: km/h; abbreviations: kph, kmph, km/hr) is a unit of speed, expressing the number of kilometres travelled in one hour.

## Mach

Mach, sometimes also referred to as a Mach number, is a speed measurement based on the speed of sound. Since sound travels at different speeds in different conditions, the calculations here are given for 20°C in dry air at sea level.

## Light speed

The speed of light in vacuum or Light Speed, commonly denoted c, is a fundamental universal constant, the speed at which light and all forms of electromagnetic radiation travel in a vacuum.It is important in many areas of physics. Its exact value is defined as 299792458 metres per second (approximately 300000 km/s or 186000 mi/s).