Millimeters to Light-minutes (mm to lmin)

1 millimeter equals 5.559401587×10⁻¹⁴ light-minutes (rounded).

1 millimeter = 5.559401587×10⁻¹⁴ light-minutes

How to convert millimeters to light-minutes

To convert millimeters to light-minutes, multiply the number of millimeters by 5.559401587×10⁻¹⁴. The factor is rounded to 10 significant digits. To go the other way, multiply light-minutes by 17,987,547,480,000.

light-minutes = millimeters × 5.559401587×10⁻¹⁴

Example: 10 millimeters = 5.559401587×10⁻¹³ light-minutes.

About these units

Millimeter (mm)

Metric (SI)Current unit

One thousandth of a meter. Used in engineering, manufacturing and rainfall measurement.

Carl Friedrich Gauss put the millimeter at the base of his 1832 proposal for absolute units, pairing it with the milligram and the second, although the centimeter-based CGS system later won out among scientists. The name combines the metric prefix milli-, from the Latin for one thousand, with the meter. Since 1983 a millimeter has been tied to the speed of light: it is the distance light covers in 1/299,792,458,000 of a second.

Millimeters are the language of fine mechanical work. Standard rulers are divided into them, digital calipers commonly read to 0.01 mm, and mechanical pencil leads come in 0.5 and 0.7 mm. Copy paper is about 0.1 mm thick, and a thin hair, at 0.02 to 0.04 mm across, is close to the smallest thing the naked eye can see. A wave with a frequency of 300 GHz has a wavelength of 1 mm. An inch is exactly 25.4 mm. One trap for readers in the United States is that mil there traditionally means a thousandth of an inch, not a millimeter.

1 millimeter = 0.001 meters (exactly).

Sources: Wikipedia: Millimetre; Wikipedia: Centimetre-gram-second system of units; NIST Guide to the SI, Appendix B.8: conversion factors

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.