# Speed of Light Conversion Calculator

Enter a value in speed of light below to convert to another unit of speed.

**Results:**

## What Is the Speed of Light?

The speed of light is a unit used to measure speed.

Speed of light can be abbreviated as *c*; for example, 1 speed of light can be written as 1 c.

## How Fast Is the Speed of Light?

The speed of light is equal to exactly 299,792,458 meters per second, or 670,616,629 miles per hour.
The definition of the speed of light is actually derived from the most recent 1983 international definition of the meter.^{[1]}

## How to Convert the Speed of Light

To convert speed of light to another unit of speed, you need to multiply the value by a conversion factor.
A conversion factor is a numerical value used to change the units of a measurement without changing the value.^{[2]}

You can find the conversion factors for speed of light in the conversion table below.

Then, multiply the speed measurement by the conversion factor to find the equivalent value in the desired unit of measurement.

speed of light × conversion factor = result

You can also use a calculator, such as one of the converters below, for the conversion.

## Speed of Light Conversion Table

speed of light | knots | Mach number | speed of sound | miles per hour | feet per second | kilometers per second | kilometers per hour | meters per second | centimeters per second |
---|---|---|---|---|---|---|---|---|---|

1 c | 582,749,918 kn | Mach 874,030 | 874,030 sound | 670,616,629 mph | 983,571,056 ft/s | 299,792 km/s | 1,079,252,849 km/h | 299,792,458 m/s | 29,979,245,800 cm/s |

2 c | 1,165,499,837 kn | Mach 1,748,061 | 1,748,061 sound | 1,341,233,259 mph | 1,967,142,113 ft/s | 599,585 km/s | 2,158,505,698 km/h | 599,584,916 m/s | 59,958,491,600 cm/s |

3 c | 1,748,249,755 kn | Mach 2,622,091 | 2,622,091 sound | 2,011,849,888 mph | 2,950,713,169 ft/s | 899,377 km/s | 3,237,758,546 km/h | 899,377,374 m/s | 89,937,737,400 cm/s |

4 c | 2,330,999,673 kn | Mach 3,496,122 | 3,496,122 sound | 2,682,466,518 mph | 3,934,284,226 ft/s | 1,199,170 km/s | 4,317,011,395 km/h | 1,199,169,832 m/s | 119,916,983,200 cm/s |

5 c | 2,913,749,592 kn | Mach 4,370,152 | 4,370,152 sound | 3,353,083,147 mph | 4,917,855,282 ft/s | 1,498,962 km/s | 5,396,264,244 km/h | 1,498,962,290 m/s | 149,896,229,000 cm/s |

6 c | 3,496,499,510 kn | Mach 5,244,183 | 5,244,183 sound | 4,023,699,776 mph | 5,901,426,339 ft/s | 1,798,755 km/s | 6,475,517,093 km/h | 1,798,754,748 m/s | 179,875,474,800 cm/s |

7 c | 4,079,249,429 kn | Mach 6,118,213 | 6,118,213 sound | 4,694,316,406 mph | 6,884,997,395 ft/s | 2,098,547 km/s | 7,554,769,942 km/h | 2,098,547,206 m/s | 209,854,720,600 cm/s |

8 c | 4,661,999,347 kn | Mach 6,992,244 | 6,992,244 sound | 5,364,933,035 mph | 7,868,568,451 ft/s | 2,398,340 km/s | 8,634,022,790 km/h | 2,398,339,664 m/s | 239,833,966,400 cm/s |

9 c | 5,244,749,265 kn | Mach 7,866,274 | 7,866,274 sound | 6,035,549,664 mph | 8,852,139,508 ft/s | 2,698,132 km/s | 9,713,275,639 km/h | 2,698,132,122 m/s | 269,813,212,200 cm/s |

10 c | 5,827,499,184 kn | Mach 8,740,305 | 8,740,305 sound | 6,706,166,294 mph | 9,835,710,564 ft/s | 2,997,925 km/s | 10,792,528,488 km/h | 2,997,924,580 m/s | 299,792,458,000 cm/s |

11 c | 6,410,249,102 kn | Mach 9,614,335 | 9,614,335 sound | 7,376,782,923 mph | 10,819,281,621 ft/s | 3,297,717 km/s | 11,871,781,337 km/h | 3,297,717,038 m/s | 329,771,703,800 cm/s |

12 c | 6,992,999,020 kn | Mach 10,488,366 | 10,488,366 sound | 8,047,399,553 mph | 11,802,852,677 ft/s | 3,597,509 km/s | 12,951,034,186 km/h | 3,597,509,496 m/s | 359,750,949,600 cm/s |

13 c | 7,575,748,939 kn | Mach 11,362,396 | 11,362,396 sound | 8,718,016,182 mph | 12,786,423,734 ft/s | 3,897,302 km/s | 14,030,287,034 km/h | 3,897,301,954 m/s | 389,730,195,400 cm/s |

14 c | 8,158,498,857 kn | Mach 12,236,427 | 12,236,427 sound | 9,388,632,811 mph | 13,769,994,790 ft/s | 4,197,094 km/s | 15,109,539,883 km/h | 4,197,094,412 m/s | 419,709,441,200 cm/s |

15 c | 8,741,248,775 kn | Mach 13,110,457 | 13,110,457 sound | 10,059,249,441 mph | 14,753,565,846 ft/s | 4,496,887 km/s | 16,188,792,732 km/h | 4,496,886,870 m/s | 449,688,687,000 cm/s |

16 c | 9,323,998,694 kn | Mach 13,984,488 | 13,984,488 sound | 10,729,866,070 mph | 15,737,136,903 ft/s | 4,796,679 km/s | 17,268,045,581 km/h | 4,796,679,328 m/s | 479,667,932,800 cm/s |

17 c | 9,906,748,612 kn | Mach 14,858,518 | 14,858,518 sound | 11,400,482,700 mph | 16,720,707,959 ft/s | 5,096,472 km/s | 18,347,298,430 km/h | 5,096,471,786 m/s | 509,647,178,600 cm/s |

18 c | 10,489,498,530 kn | Mach 15,732,549 | 15,732,549 sound | 12,071,099,329 mph | 17,704,279,016 ft/s | 5,396,264 km/s | 19,426,551,278 km/h | 5,396,264,244 m/s | 539,626,424,400 cm/s |

19 c | 11,072,248,449 kn | Mach 16,606,579 | 16,606,579 sound | 12,741,715,958 mph | 18,687,850,072 ft/s | 5,696,057 km/s | 20,505,804,127 km/h | 5,696,056,702 m/s | 569,605,670,200 cm/s |

20 c | 11,654,998,367 kn | Mach 17,480,610 | 17,480,610 sound | 13,412,332,588 mph | 19,671,421,129 ft/s | 5,995,849 km/s | 21,585,056,976 km/h | 5,995,849,160 m/s | 599,584,916,000 cm/s |

## Speed of Light Conversion Calculators

You can also convert speed using one of our speed of light converters below.

- speed of light to knots converter
- speed of light to Mach number converter
- speed of light to speed of sound converter
- speed of light to miles per hour converter
- speed of light to feet per second converter
- speed of light to kilometers per second converter
- speed of light to kilometers per hour converter
- speed of light to meters per second converter
- speed of light to centimeters per second converter

## References

- National Institute of Standards and Technology, SI Redefinition: Meter, https://www.nist.gov/si-redefinition/meter
- National Institute of Standards & Technology, Unit Conversion, https://www.nist.gov/pml/owm/metric-si/unit-conversion