Convert fathoms to light years

1 ftm=1.9330e-16ly

Use the converter below to change any fathoms value into light years instantly — with formula, conversion table, and real-world examples.

You have

Equals

1.9330e-16

Conversion formula

Forward

light years = fathoms × 1.9330e-16

Reverse

fathoms = light years × 5.1732e15

Example: 10 ftm × 1.9330e-16 = 1.9330e-15 ly.

About both units

From

Fathom

ftm

The fathom equals exactly 6 feet or 1.8288 meters. It is the traditional marine unit for water depth, used on older nautical charts and in recreational sailing. Modern charts mark depths in metres, but fathoms still appear in maritime literature and older US charts.

Real-world: A "mark twain" reading — made famous by the Mississippi riverboats — meant 2 fathoms (3.66 m) of water, the minimum safe depth.

Read full fathom reference →

Light Year

A light year is the distance light travels in one Julian year — approximately 9.461 × 10¹⁵ meters, or 63,241 AU. It is used in astronomy to describe distances between stars and galaxies. The nearest star to the Sun, Proxima Centauri, is 4.24 light years away.

Real-world: Proxima Centauri, the nearest star beyond the Sun, is 4.24 ly away. The Milky Way is about 100,000 ly across.

Read full light year reference →

Fathom to Light Year conversion table

Common fathoms to light years values for quick reference.

Fathom (ftm)	Light Year (ly)
1 ftm	1.9330e-16 ly
5 ftm	9.6652e-16 ly
10 ftm	1.9330e-15 ly
25 ftm	4.8326e-15 ly
50 ftm	9.6652e-15 ly
100 ftm	1.9330e-14 ly
250 ftm	4.8326e-14 ly
500 ftm	9.6652e-14 ly
1,000 ftm	1.9330e-13 ly
5,000 ftm	9.6652e-13 ly

Tips & common mistakes

Quick tips

1 fathom = 2 yards = 6 feet = 1.8288 m.
Modern charts use metres internationally; fathoms are mostly historical.
The word "fathom" comes from Old English for "outstretched arms" — originally the span of an adult's arms.

Avoid these

Reading a modern chart that uses metres as if it were fathoms — a factor-of-1.83 depth error.
Confusing fathoms with feet on mixed-unit charts.
Assuming all US charts still use fathoms — NOAA has largely migrated to metres.

Frequently asked questions

How many light years in a fathom?

One fathom equals 1.9330e-16 light years.

How do I convert fathoms to light years?

Multiply the fathom value by 1.9330e-16 to get the equivalent in light years.

What is 100 fathoms in light years?

100 fathoms equals 1.9330e-14 light years.

Is a fathom bigger than a light year?

No. 1 fathom equals 1.9330e-16 light years, so one fathom is smaller.

How to convert fathoms to light years without a calculator?

Multiply by 0 for a quick estimate; use a calculator for precise results.

Related length conversions

📊 See full comparison matrix →

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