Kilometer/Second to Speed of Light Converter

Speed Converter

18 units available

Decimals:

From

To

3.335641e-6

1 km/s = 3.335641e-6 c

Formula:

c = km/s × 0.0000033356

With your value: 1 km/s = 3.335641e-6 c

How big is that?

Everyday references on a logarithmic scale, all expressed in kilometer/second so you can sanity-check the result.

Urban speed limit (50 km/h) (1/72 your value)0.0139 km/s

Cheetah sprint (1/34 your value)0.0290 km/s

Motorway (110 km/h) (1/33 your value)0.0306 km/s

Airliner cruise (1/4.0 your value)0.250 km/s

Speed of sound (sea level) (1/2.9 your value)0.343 km/s

Your value1.00 km/s

Other Kilometer/Second to Speed of Light conversions

2 km/s to c 3 km/s to c 4 km/s to c 5 km/s to c 6 km/s to c 7 km/s to c 8 km/s to c

Kilometer/Second to Speed of Light Conversion Table

Kilometer/Second (km/s)	Speed of Light (c)
0.5	1.667820e-6
1	3.335641e-6
2	6.671282e-6
5	1.667820e-5
10	3.335641e-5
15	5.003461e-5
20	6.671282e-5
25	8.339102e-5
50	0.000167
100	0.000334
250	0.000834
500	0.001668
1000	0.003336

Speed of Light to Kilometer/Second Conversion Table

Speed of Light (c)	Kilometer/Second (km/s)
0.5	149,896.229
1	299,792.458
2	599,584.916
5	1,498,962.29
10	2,997,924.58
15	4,496,886.87
20	5,995,849.16
25	7,494,811.45
50	14,989,622.9
100	29,979,245.8
250	74,948,114.5
500	149,896,229
1000	299,792,458

Where these values come from

Every factor on this page is traced to the document that defines it. See the full provenance dataset or our methodology.

Kilometer/Second (km/s)

Speed

Exact conversion

Derived quantity: a defined length divided by a defined time interval.

Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)

Bureau International des Poids et Mesures · Reviewed 2026-07-01

Speed of Light (c)

Speed

Exact conversion

Derived quantity: a defined length divided by a defined time interval.

Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)

Bureau International des Poids et Mesures · Reviewed 2026-07-01

How to Convert Kilometer/Second to Speed of Light

To convert from Kilometer/Second (km/s) to Speed of Light (c), multiply the value by 3.335641e-6.

Formula: c = km/s × 0.0000033356

Reverse: km/s = c × 299,792.458

Step-by-Step Example

Start with your value in Kilometer/Second. For example: 5 km/s
Multiply by the conversion factor: 5 x 3.335641e-6
The result is: 1.667820e-5 c

About Kilometer/Second

The kilometer/second (km/s) is a unit of speed and velocity. One kilometer/second equals 1000 metre per seconds. UnitConvertLab converts it against every other speed unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

Common uses: speed calculations, engineering and science, education.

About Speed of Light

The speed of light (c) is a unit of speed and velocity. One speed of light equals 2.997925 × 10^+8 metre per seconds. UnitConvertLab converts it against every other speed unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

Common uses: speed calculations, engineering and science, education.

Frequently Asked Questions

How many Speed of Light are in 1 Kilometer/Second?

There are exactly 3.335641e-6 Speed of Light in 1 Kilometer/Second. This means the conversion factor from Kilometer/Second to Speed of Light is 3.335641e-6.

What is the formula to convert Kilometer/Second to Speed of Light?

The formula to convert Kilometer/Second to Speed of Light is: c = km/s × 0.0000033356. For example, to convert 10 Kilometer/Second to Speed of Light, you would multiply 10 by 3.335641e-6.

What is a Kilometer/Second?