Fathom to Light Year Converter
Convert Fathom (ftm) to Light Year (ly) instantly. 1 ftm = 1.933043e-16 ly.
Length Converter
31 units available
1 ftm = 1.933043e-16 ly
Formula:
ly = ftm × 1.933043e-16With your value: 1 ftm = 1.933043e-16 ly
How big is that?
Everyday references on a logarithmic scale, all expressed in fathom so you can sanity-check the result.
Other Fathom to Light Year conversions
Fathom to Light Year Conversion Table
| Fathom (ftm) | Light Year (ly) |
|---|---|
| 0.5 | 9.665216e-17 |
| 1 | 1.933043e-16 |
| 2 | 3.866086e-16 |
| 5 | 9.665216e-16 |
| 10 | 1.933043e-15 |
| 15 | 2.899565e-15 |
| 20 | 3.866086e-15 |
| 25 | 4.832608e-15 |
| 50 | 9.665216e-15 |
| 100 | 1.933043e-14 |
| 250 | 4.832608e-14 |
| 500 | 9.665216e-14 |
| 1000 | 1.933043e-13 |
Light Year to Fathom Conversion Table
| Light Year (ly) | Fathom (ftm) |
|---|---|
| 0.5 | 2.586595e+15 |
| 1 | 5.173190e+15 |
| 2 | 1.034638e+16 |
| 5 | 2.586595e+16 |
| 10 | 5.173190e+16 |
| 15 | 7.759785e+16 |
| 20 | 1.034638e+17 |
| 25 | 1.293298e+17 |
| 50 | 2.586595e+17 |
| 100 | 5.173190e+17 |
| 250 | 1.293298e+18 |
| 500 | 2.586595e+18 |
| 1000 | 5.173190e+18 |
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.
Fathom (ftm)
Length
Traceable to the metre, defined by fixing the speed of light in vacuum at 299 792 458 m/s. Imperial lengths derive from the 1959 international yard (0.9144 m exactly).
Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)
Bureau International des Poids et Mesures · Reviewed 2026-07-01
Light Year (ly)
Length
A light-year is the distance light travels in one Julian year: 9 460 730 472 580 800 m exactly.
Source: IAU Resolution B2 (2012) — definition of the astronomical unit; IAU B2 (2015) nominal values
International Astronomical Union · Reviewed 2026-07-01
How to Convert Fathom to Light Year
To convert from Fathom (ftm) to Light Year (ly), multiply the value by 1.933043e-16.
Formula: ly = ftm × 1.933043e-16
Reverse: ftm = ly × 5.173190e+15
Step-by-Step Example
- Start with your value in Fathom. For example: 5 ftm
- Multiply by the conversion factor: 5 x 1.933043e-16
- The result is: 9.665216e-16 ly
About Fathom
The fathom equals 6 feet (1.8288 m) and is the traditional unit for water depth on nautical charts.
Fun Fact: The word comes from the Old English "fæðm", the span of a man's outstretched arms.
Common uses: sounding depth, nautical charts, diving.
About Light Year
A light year is the distance light travels through a vacuum in one Julian year — exactly 9,460,730,472,580,800 metres. It is a unit of distance, not of time.
Fun Fact: Proxima Centauri, the nearest star to the Sun, sits about 4.25 light years away.
Common uses: astronomy, popular science, education.
Frequently Asked Questions
How many Light Year are in 1 Fathom?
There are exactly 1.933043e-16 Light Year in 1 Fathom. This means the conversion factor from Fathom to Light Year is 1.933043e-16.
What is the formula to convert Fathom to Light Year?
The formula to convert Fathom to Light Year is: ly = ftm × 1.933043e-16. For example, to convert 10 Fathom to Light Year, you would multiply 10 by 1.933043e-16.
What is a Fathom?
The fathom equals 6 feet (1.8288 m) and is the traditional unit for water depth on nautical charts.
What is a Light Year?
A light year is the distance light travels through a vacuum in one Julian year — exactly 9,460,730,472,580,800 metres. It is a unit of distance, not of time.
What are the common uses of Fathom?
The Fathom is commonly used in sounding depth, nautical charts, diving.
Related Length Conversions
Cite this page
UnitConvertLab. (2026). Fathom to Light Year converter. UnitConvertLab. Retrieved from https://unitconvertlab.com/convert/fathom-to-light_year