Fathom to Parsec Conversion Calculator: Free Online Tool
Convert fathoms to parsecs with our free online length converter.
Fathom to Parsec Calculator
How to Use the Calculator:
- Enter the value you want to convert in the 'From' field (Fathom).
- The converted value in Parsec will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Length category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Fathom to Parsec
Converting Fathom to Parsec involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Fathom = 5.9267e-17 parsecsExample Calculation:
Convert 10 fathoms: 10 × 5.9267e-17 = 5.9267e-16 parsecs
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
What is a Fathom and a Parsec?
The Fathom (symbol fath) is a unit of length in the imperial and U.S. customary systems of measurement, defined as exactly 6 feet (ft). This is equivalent to 2 yards or 1.8288 meters (m). It is almost exclusively used in maritime contexts for measuring the depth of water.
The Parsec (symbol pc) is a unit of length used to measure the enormous distances to astronomical objects outside the Solar System. One parsec is defined as the distance at which one astronomical unit (AU) – the average distance between the Earth and the Sun – subtends an angle of one arcsecond (1/3600th of a degree). This corresponds to approximately:
- 3.0857 × 10¹⁶ meters (m)
- 30.857 trillion kilometers (km)
- 19.174 trillion miles (mi)
- 206,264.8 astronomical units (AU)
- 3.26156 light-years (ly)
It is derived directly from the method of trigonometric parallax used by astronomers to measure stellar distances.
Note: The Fathom is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Parsec belongs to the imperial/US customary system.
History of the Fathom and Parsec
The word "fathom" originates from the Old English word fæthm, meaning "a pair of outstretched arms" or "embrace". Historically, the length was derived from the distance between the fingertips of a man's outstretched arms, a practical method for sailors measuring the length of a sounding line (a rope with a weight used to measure water depth) as they hauled it in. This naturally variable measure was eventually standardized to precisely 6 feet. For centuries, it was the primary unit for depth soundings on nautical charts and in maritime operations in English-speaking countries and beyond. While its official use has declined with metrication, it remains a significant unit in nautical tradition.
The concept of measuring stellar distances via parallax existed long before the unit itself. The term "parsec" was coined by the British astronomer Herbert Hall Turner in 1913. He sought a convenient unit for astronomers that directly reflected the observational method. The name is a portmanteau derived from "parallax of one arcsecond". It quickly gained acceptance within the astronomical community due to its practical connection to parallax measurements, which were (and still are) a fundamental way to determine distances to nearby stars.
Common Uses for fathoms and parsecs
Explore the typical applications for both Fathom (imperial/US) and Parsec (imperial/US) to understand their common contexts.
Common Uses for fathoms
The fathom's use is strongly tied to the sea:
- Hydrography & Navigation: Measuring water depth (soundings) on nautical charts. Many charts, particularly older ones or those used in the US and UK, still use fathoms. Contour lines showing seabed depth are often called "fathom lines".
- Nautical Terminology: Used historically to measure the length of ropes and anchor cables (e.g., a "cable length" was often defined as 100 or 120 fathoms).
- Commercial Fishing: Sometimes used by fishermen to describe the length of nets or fishing lines, or the depth at which they are fishing.
- Literature & Figurative Language: Frequently appears in maritime literature (e.g., "full fathom five" from Shakespeare's The Tempest). Metaphorically, "to fathom" means to comprehend or get to the bottom of something complex.
- Historical Land Measurement: Very occasionally used in historical land surveying or mining contexts, but this was rare compared to its maritime use.
Common Uses for parsecs
The parsec is the preferred unit of distance in professional astronomy and astrophysics:
- Stellar Distances: Measuring distances to nearby stars using parallax.
- Galactic Structure: Describing distances within the Milky Way galaxy (often using kiloparsecs, kpc, where 1 kpc = 1000 pc). For example, the Sun is about 8 kpc from the Galactic Center.
- Extragalactic Distances: Measuring distances to other galaxies and galaxy clusters (often using megaparsecs, Mpc, where 1 Mpc = 1,000,000 pc). The Hubble constant, describing the expansion of the universe, is typically expressed in (km/s)/Mpc.
- Cosmology: Discussing large-scale structures and distances in the universe (using Mpc and sometimes gigaparsecs, Gpc, where 1 Gpc = 1000 Mpc).
Frequently Asked Questions
Questions About Fathom (fath)
How many feet are in a fathom?
There are exactly 6 feet (ft) in 1 fathom.
How many meters are in a fathom?
One fathom is equal to exactly 1.8288 meters (m).
Is the fathom an SI unit?
No, the fathom is not an SI unit. It is part of the imperial and U.S. customary systems. The corresponding SI unit for length is the meter (m).
Is the fathom still commonly used today?
Its usage has decreased significantly due to the widespread adoption of the metric system in international shipping and hydrography. However, it remains common on nautical charts produced by countries like the United States and the United Kingdom, and it persists in recreational boating, commercial fishing communities, maritime tradition, and literature. Modern international charts increasingly use meters for depth soundings.
Where does the word 'fathom' come from?
The word originates from the Old English fæthm, which referred to the span of a person's outstretched arms. This distance was the practical basis for the original measurement used by sailors.
About Parsec (pc)
What does 'Parsec' stand for?
Parsec is a blend of "parallax of one arcsecond". It represents the distance at which the parallax angle of a star is exactly one second of arc.
How is a parsec defined?
It's defined based on trigonometry. Imagine a right-angled triangle in space where the short side is the Earth-Sun distance (1 AU). The parsec is the length of the adjacent side when the angle at the distant star (the parallax angle) is exactly one arcsecond.
Is a Parsec bigger than a Light Year?
Yes, one parsec is significantly larger than one light-year.
- 1 Parsec ≈ 3.26 light-years
How many meters or kilometers are in a parsec?
One parsec is approximately:
- 3.0857 × 10¹⁶ meters
- 30.857 trillion kilometers
How many Astronomical Units (AU) are in a parsec?
One parsec is equal to approximately 206,265 AU. This number arises directly from the definition involving radians and arcseconds (specifically, the number of arcseconds in a radian).
Why do astronomers use parsecs instead of light-years?
While both are used, parsecs are often preferred in professional contexts because:
- Direct Observational Link: The parsec is derived directly from the parallax angle, a primary method for measuring distance.
- Historical Convention: It became the standard unit early in the development of stellar distance measurement.
- Convenience: Multiples like kpc and Mpc provide convenient scales for galactic and extragalactic distances.
- Definition Stability: The definition of a light-year depends slightly on the definition of a "year" (e.g., Julian year), whereas the parsec is based on the fixed AU and geometric angles.
Is the parsec an SI unit?
No, the parsec is not an SI unit. The SI unit for length is the meter (m). However, the parsec (along with the astronomical unit and light-year) is recognized by the International Astronomical Union (IAU) and is widely accepted for use in astronomy.
Conversion Table: Fathom to Parsec
| Fathom (fath) | Parsec (pc) |
|---|---|
| 1 | 0 |
| 5 | 0 |
| 10 | 0 |
| 25 | 0 |
| 50 | 0 |
| 100 | 0 |
| 500 | 0 |
| 1,000 | 0 |
All Length Conversions
Other Units from Length
- Meter (m)
- Kilometer (km)
- Hectometer (hm)
- Decimeter (dm)
- Centimeter (cm)
- Millimeter (mm)
- Inch (in)
- Foot (ft)
- Yard (yd)
- Mile (mi)
- Nautical Mile (NM)
- Micrometer (μm)
- Nanometer (nm)
- Light Year (ly)
- Astronomical Unit (AU)
- Angstrom (Å)
- Point (Typography) (pt)
- Mil/Thou (mil)
- Furlong (fur)
- Link (Gunter's) (li)
- Pace (pace)
- Span (span)
- Digit (digit)
- Cable Length (cb)
- Ell (ell)
- Finger (finger)
- Roman Mile (m.p.)
- Stadion (stadion)
- Chi (Chinese) (chi)
- Shaku (Japanese) (shaku)
- Li (Chinese) (li)
- Toise (toise)
- Bolt (bolt)
- Rope (rope)
- Smoot (smoot)
- Sajene (sajene)
- Ken (ken)
- Wa (wa)
- Vara (vara)
- Aln (aln)
- Cubit (Royal/Egyptian) (cubit)
- Versta (versta)
- Arpent (arpent)
- Ri (Japanese) (ri)
- Klafter (klafter)
- Yojana (yojana)
- Skein (skein)