Speed Of Light to Meters Per Second (c to m/s)

1 speed of light equals 299,792,458 meters per second exactly.

1 speed of light = 299,792,458 meters per second

How to convert speed of light to meters per second

To convert speed of light to meters per second, multiply the number of speed of light by 299,792,458. This factor is exact. To go the other way, multiply meters per second by 3.335640952×10⁻⁹ (rounded).

meters per second = speed of light × 299,792,458

Example: 10 speed of light = 2,997,924,580 meters per second.

About these units

Speed Of Light (c)

ScientificCurrent unit

Exactly 299,792,458 m/s, the speed of light in a vacuum and the fundamental constant that defines the meter.

Light was once thought to arrive instantly. In 1676 Ole Rømer timed eclipses of Jupiter's moon Io and concluded that light takes about 22 minutes to cross Earth's orbit. In 1729 James Bradley used the aberration of starlight to estimate about 8 minutes 12 seconds from Sun to Earth. Later experimenters used a toothed wheel (Fizeau), a rotating mirror (Foucault), and in 1930 to 1935 Michelson, Pease and Pearson used a mile-long vacuum chamber. The letter c is itself uncertain: it may stand for constant or the Latin celeritas, swiftness, and Einstein switched to it in 1907.

Since 1983 the speed of light has been fixed at exactly 299,792,458 m/s, and the meter is defined as the distance light travels in a vacuum in 1/299,792,458 of a second. Measurement therefore became a matter of defining the constant, not of improving experiments. For scale, light takes about 1.3 seconds to travel from the Earth to the Moon, about 8.3 minutes from the Sun, and roughly one nanosecond to go a foot. James Clerk Maxwell showed in 1865 that light is an electromagnetic wave.

1 speed of light = 299,792,458 meters per second (exactly).

Sources: Wikipedia: Speed of light; NIST: the meter and the SI redefinition

Meter Per Second (m/s)

Metric (SI)Current unit

The SI unit of speed. Walking pace is about 1.4 m/s; a sprinter reaches roughly 10 m/s.

Official standing arrived in 1960, when the CGPM established the SI and made the meter per second the unit for speed and velocity. Before that, feet per second, miles per hour and knots were more common, depending on region and trade. One proposal gave 1 m/s its own name, the benz, after Karl Benz, but it was rejected and never caught on, so the unit is still written as a plain ratio of meter to second.

The meter is now defined by the distance light travels in a vacuum in 1/299,792,458 of a second, and the second by the vibration of caesium atoms, so the meter per second rests on two physical standards. Exactly 3.6 km/h make 1 m/s, and it equals about 2.2369 mph or 1.9438 knots. For scale, sound travels at about 343 m/s in dry air at 20 °C, and Chuck Yeager's Bell X-1 reached about 361 m/s, Mach 1.06, in October 1947. Physics and engineering use the unit almost exclusively.

The meter per second is the reference unit for speed on this site.

Sources: Wikipedia: Metre per second; NIST: the meter and the SI redefinition; Wikipedia: Sound barrier

Related conversions

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