Convert Speed of Light to Kilometres per Second

Convert Speed of Light (c) to Kilometres per Second (km/s) instantly and accurately.

Conversion Formula

km/s = c × 299792.458

About Speed of Light

The speed of light in vacuum (c) = exactly 299,792,458 m/s - the defined SI constant from which the metre is derived (since 1983) and the universal speed limit of causality. Light from the Sun reaches Earth in 8 min 20 s; from the Moon in 1.28 s; from Proxima Centauri in 4.24 years. Mars communication delay 3-22 minutes. In optical fibre (n ≈ 1.467), c/n ≈ 200,000 km/s. GPS clocks must correct for both special and general relativistic effects. c = 299,792,458 m/s.

About Kilometres per Second

A kilometre per second (km/s) = 1,000 m/s - the scale of orbital mechanics and hypervelocity. ISS orbital speed ≈ 7.66 km/s; Earth escape velocity 11.186 km/s. Voyager 1 travels ~17 km/s relative to the Sun. Meteoroids enter Earth's atmosphere at 11-72 km/s; solar wind 400-800 km/s. High-explosive detonation fronts propagate at 6.9-8.8 km/s. 1 km/s = 3,600 km/h = 2,236.9 mph.

Quick Reference Table

→ Full Speed Converter