Fraction of light speed to kilometers per second
Type a value in c to get it in km/s instantly.
269,813.2km/s
That's about the same as 90% of light speed. A year aboard would be about 2.294 years back home.
What it means
How relativistic is that?
These are the effects for steady motion in a straight line. Acceleration and gravity add their own, which is general relativity rather than special.
The math
How to convert c to km/s
The Lorentz factor is γ = 1 ÷ √(1 − v²/c²), and back again v = c × √(1 − 1/γ²). Time dilation is γ, length contraction is 1/γ, and the kinetic energy is (γ − 1) times mc².
Example: 0.9 c = 269,813 km/s.
Every unit
Your speed in every unit
Tables
c to km/s conversion table
| c | km/s |
|---|---|
| 0.01 c | 2,997.92 km/s |
| 0.1 c | 29,979.2 km/s |
| 0.3 c | 89,937.7 km/s |
| 0.5 c | 149,896 km/s |
| 0.6 c | 179,875 km/s |
| 0.8 c | 239,834 km/s |
| 0.9 c | 269,813 km/s |
| 0.95 c | 284,803 km/s |
| 0.99 c | 296,795 km/s |
| 0.999 c | 299,493 km/s |
km/s to c conversion table
| km/s | c |
|---|---|
| 3,000 km/s | 0.0100069 c |
| 30,000 km/s | 0.100069 c |
| 89,900 km/s | 0.299874 c |
| 150,000 km/s | 0.500346 c |
| 180,000 km/s | 0.600415 c |
| 240,000 km/s | 0.800554 c |
| 270,000 km/s | 0.900623 c |
| 285,000 km/s | 0.950658 c |
| 297,000 km/s | 0.990685 c |
| 299,000 km/s | 0.997357 c |
Quick answers
Quick answers
- How many km/s is 0.9 c?
- 0.9 c is 269,813 km/s.
The units
About these units
Fraction of light speed (c)
The speed as a fraction of c.
Kilometers per second (km/s)
The speed in everyday units. Light does 299,792.
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