299792

299792 is an integer that is sometimes used as a rounded representation of the speed of light in vacuum when expressed in kilometers per second. The exact speed of light in vacuum is defined as 299,792,458 meters per second, which equals 299,792.458 kilometers per second.

Because the scientific convention fixes c as an exact quantity in meters per second, 299,792 km/s is the nearest-kilometer-per-second rounding of the speed of light, and is used as an approximation in calculations that do not require more precision.

299,792 is not a physical constant by itself; it is a derived rounded figure from c. In contexts requiring precision, the decimal 299,792.458 km/s or the exact 299,792,458 m/s is used.

See also: speed of light; fundamental physical constants; SI units.