Light-years to Feet (ly to ft)

1 light-year equals 3.103914197×10¹⁶ feet (rounded).

1 light-year = 3.103914197×10¹⁶ feet

How to convert light-years to feet

To convert light-years to feet, multiply the number of light-years by 3.103914197×10¹⁶. The factor is rounded to 10 significant digits. To go the other way, multiply feet by 3.221738542×10⁻¹⁷ (rounded).

feet = light-years × 3.103914197×10¹⁶

Example: 10 light-years = 3.103914197×10¹⁷ feet.

About these units

Light-year (ly)

AstronomicalCurrent unit

The distance light travels in one Julian year: exactly 9,460,730,472,580,800 meters (about 9.46 trillion km).

Despite the name, a light-year measures distance rather than time, and its coinage is a little later than most people assume. Friedrich Bessel measured the distance to the star 61 Cygni in 1838 but did not use the unit himself. The light-year appeared in print in 1851, in a German article by Otto Ule, who explained its odd use of a time word by comparing it to saying that a place is an hour's walk away.

The International Astronomical Union defines it as the distance light travels in a vacuum in one Julian year of 365.25 days, about 9.46 trillion kilometers. NIST lists it as 9.460 73 times 10 to the 15th meters. Light-years dominate popular science, while professional astronomers mostly prefer the parsec, about 3.26 light-years. For scale, Proxima Centauri, the nearest star to the Sun, is about 4.24 light-years away, and the Milky Way is roughly 100,000 light-years across.

1 light-year = 9.460730473×10¹⁵ meters (approximately).

Sources: Wikipedia: Light-year; NIST Guide to the SI, Appendix B.8: conversion factors

Foot (ft)

US & ImperialCurrent unit

12 inches. Defined as exactly 0.3048 meters. Still the standard unit for height, altitude in aviation and room dimensions in the US and UK.

Human anatomy supplied the idea: an adult foot is roughly 15 percent of body height. Ancient cultures turned that into standards, but not the same one. The Greek pous was about 302 mm, the standard Roman pes about 295.7 mm, and a Harappan foot of about 335 mm has been reported from the Indus Valley. Historically, a foot fell somewhere between about 250 and 335 mm. Charlemagne tried to standardize units around 790 with little lasting success, and in 1593 English law fixed the statute mile at 5,280 feet.

The modern foot dates from the 1959 International Yard and Pound Agreement, which defined the yard as exactly 0.9144 meter and so the foot as exactly 0.3048 meter; the UK adopted it on 1 January 1964. The US survey foot, defined in 1893 as 1200/3937 meter, was deprecated on 31 December 2022. Feet remain in everyday use for height and rooms in the US, and ISO shipping containers are defined in them. Aviation altitudes use them too: flight level 330 means 33,000 feet.

1 foot = 0.3048 meters (exactly).

Sources: Wikipedia: Foot (unit); Wikipedia: Mile; NIST Guide to the SI, Appendix B.8: conversion factors

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