Kilometers to Light-minutes (km to lmin)

1 kilometer equals 5.559401587×10⁻⁸ light-minutes (rounded).

1 kilometer = 5.559401587×10⁻⁸ light-minutes

How to convert kilometers to light-minutes

To convert kilometers to light-minutes, multiply the number of kilometers by 5.559401587×10⁻⁸. The factor is rounded to 10 significant digits. To go the other way, multiply light-minutes by 17,987,547.48.

light-minutes = kilometers × 5.559401587×10⁻⁸

Example: 10 kilometers = 5.559401587×10⁻⁷ light-minutes.

About these units

Kilometer (km)

Metric (SI)Current unit

1,000 meters. The standard unit for road distances in most countries.

A name for 1,000 meters took a while to settle. In 1793 France's National Convention made the metre the sole French unit of length, and the first proposed name for the thousand-metre multiple was millaire. Everyday French usage then leaned on the myriametre, 10,000 meters, well into the 1800s. The Netherlands adopted the kilometre in 1817, under the local name mijl, and made it the only official unit of that size in 1867. In 1935 the CIPM dropped the myria- prefix, which left the kilometre as the standard unit for road-scale distances.

Kilo- is the SI prefix for a thousand, and the kilometre is now the preferred unit for land distances in most of the world, with the United States, the United Kingdom and Liberia among those that still use the mile. One kilometre is about 0.621 mile. The main span of Lisbon's 25 de Abril Bridge, at 1.013 km, gives a sense of the scale. Even its pronunciation has been argued over: in 1970 Australia's Metric Conversion Board made stress on the first syllable official, although Prime Minister Gough Whitlam argued for stress on the second. Military slang in several countries calls it a klick.

1 kilometer = 1,000 meters (exactly).

Sources: Wikipedia: Kilometre; Wikipedia: Metric prefix; BIPM: history of the metre

Light-minute (lmin)

AstronomicalCurrent unit

The distance light travels in a minute (about 18 million km). The Sun is roughly 8.3 light-minutes from Earth.

Sunlight takes about 8.3 minutes to reach Earth, so the light-minute is the natural scale for the inner solar system. Its figure is exactly 60 light-seconds, which comes to 17,987,547,480 meters or about 18 million kilometers. The unit has no formal standing in the SI and no single inventor. It simply follows from the fixed speed of light, and it turns up in popular astronomy, in discussions of signal delays and in tables that give planetary distances as travel times.

Distance and delay are the same number in this unit, which makes it handy for spacecraft work. A signal to a distant spacecraft therefore cannot be answered instantly, because every light-minute of separation adds a minute each way. One astronomical unit is about 8.317 light-minutes, and Saturn's orbit at its closest approach to the Sun lies near 1.25 light-hours. Larger distances usually move up to light-hours or light-years.

1 light-minute = 17,987,547,480 meters (exactly).

Sources: Wikipedia: Light-minute; Wikipedia: Light-second

Related conversions

See all length units.