Convert Parsec to A.u. of Length
Convert parsecs to a.u. of length instantly. 1 parsec = 5.831086e+26 a.u. of length — use the live calculator, the exact formula, a conversion table and worked examples. Also check the A.u. of Length to Parsec converter for the reverse conversion.
Units explained
Parsec
A parsec (parallax-second) is a distance unit equal to 648,000/π astronomical units — approximately 3.086×10¹⁶ m (3.26 light years). It is the standard distance unit in professional astronomy.
Defined as the distance at which one astronomical unit subtends an angle of one arcsecond. IAU Resolution B2 in 2015 made this an exact definition: 1 pc = (648,000/π) AU.
Parsecs are used in professional astronomy for stellar distances (Proxima Centauri ≈ 1.3 pc), galactic-scale distances (with prefixes kiloparsec and megaparsec), and parallax measurements. Standard since the early 20th century.
Concept introduced by Herbert Hall Turner in 1913; exact definition via the AU adopted by IAU Resolution B2 in 2015.
A.u. of Length
The atomic unit of length (a.u.) is equal to the Bohr radius — approximately 5.292×10⁻¹¹ m. Despite the abbreviation matching 'astronomical unit', this is a different unit used in atomic and molecular physics.
The atomic unit system was developed in the 1950s for quantum-chemistry calculations. The a.u. of length is defined as the Bohr radius (a₀), the most probable distance between the proton and electron in a hydrogen atom in its ground state.
The atomic unit of length is used throughout quantum chemistry, electronic-structure theory, and computational physics. Most quantum-mechanical equations simplify when expressed in atomic units rather than SI units.
Atomic unit system developed by Hartree in the 1920s; value fixed via CODATA 2018 determination of fundamental physical constants.
Parsec to A.u. of Length conversion formula
The relationship between parsecs and a.u. of length:
To convert parsecs to a.u. of length, multiply the value in parsecs by 5.831086e+26. To reverse, multiply a.u. of length by 1.714947e-27.
How to use this converter
Type a value into the calculator. The result in a.u. of length updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the A.u. of Length to Parsec converter for the reverse direction.
Step-by-step: convert parsecs to a.u. of length
- Write down the value in parsecs (pc).
- Multiply that value by the factor 5.831086e+26.
- The product is the equivalent value in a.u. of length (a.u.).
- To reverse, multiply the a.u. of length value by 1.714947e-27.
Worked examples
Example 1 — Convert 1 pc to a.u.:
1 × 5.831086e+26 = 5.831086e+26 a.u.
Example 2 — Convert 100 pc to a.u.:
100 × 5.831086e+26 = 5.831086e+28 a.u.
Parsec to A.u. of Length conversion table
Standard reference values for converting parsecs to a.u. of length:
| Parsec [pc] | A.u. of Length [a.u.] |
|---|---|
| 0.01 | 5.831086e+24 |
| 0.1 | 5.831086e+25 |
| 1 | 5.831086e+26 |
| 2 | 1.166217e+27 |
| 3 | 1.749326e+27 |
| 4 | 2.332434e+27 |
| 5 | 2.915543e+27 |
| 10 | 5.831086e+27 |
| 20 | 1.166217e+28 |
| 30 | 1.749326e+28 |
| 40 | 2.332434e+28 |
| 50 | 2.915543e+28 |
| 100 | 5.831086e+28 |
| 500 | 2.915543e+29 |
| 1000 | 5.831086e+29 |
Frequently asked questions
How many a.u. of length is 1 parsec?
How do I convert parsecs to a.u. of length?
How do I convert a.u. of length back to parsecs?
How many a.u. of length is 100 parsecs?
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Sources & references
Conversion factor (1 pc = 5.831086e+26 a.u.) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.