Convert A.u. of Length to Parsec
Convert a.u. of length to parsecs instantly. 1 a.u. of length = 1.714947e-27 parsec — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Parsec to A.u. of Length converter for the reverse conversion.
Units explained
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
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 to Parsec conversion formula
The relationship between a.u. of length and parsecs:
To convert a.u. of length to parsecs, multiply the value in a.u. of length by 1.714947e-27. To reverse, multiply parsecs by 5.831086e+26.
How to use this converter
Type a value into the calculator. The result in parsecs updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Parsec to A.u. of Length converter for the reverse direction.
Step-by-step: convert a.u. of length to parsecs
- Write down the value in a.u. of length (a.u.).
- Multiply that value by the factor 1.714947e-27.
- The product is the equivalent value in parsecs (pc).
- To reverse, multiply the parsec value by 5.831086e+26.
Worked examples
Example 1 — Convert 1 a.u. to pc:
1 × 1.714947e-27 = 1.714947e-27 pc
Example 2 — Convert 100 a.u. to pc:
100 × 1.714947e-27 = 1.714947e-25 pc
Real-world example — Molecular dimensions
The diameter of small molecular structures (around 2 a.u. of length) is often converted into related sub-micron units when comparing measurements across different microscopy techniques or imaging modalities.
2 a.u. × 1.714947e-27 = 3.429893e-27 pc
Real-world example — Wavelengths across the spectrum
Optical and atomic-scale phenomena are routinely cross-converted between sub-micron units. A photon of wavelength 800 a.u. of length can be re-expressed in parsecs for direct comparison with another instrument's calibration data sheet.
800 a.u. × 1.714947e-27 = 1.371957e-24 pc
A.u. of Length to Parsec conversion table
Standard reference values for converting a.u. of length to parsecs:
| A.u. of Length [a.u.] | Parsec [pc] |
|---|---|
| 0.01 | 1.714947e-29 |
| 0.1 | 1.714947e-28 |
| 1 | 1.714947e-27 |
| 2 | 3.429893e-27 |
| 3 | 5.14484e-27 |
| 4 | 6.859786e-27 |
| 5 | 8.574733e-27 |
| 10 | 1.714947e-26 |
| 20 | 3.429893e-26 |
| 30 | 5.14484e-26 |
| 40 | 6.859786e-26 |
| 50 | 8.574733e-26 |
| 100 | 1.714947e-25 |
| 500 | 8.574733e-25 |
| 1000 | 1.714947e-24 |
Frequently asked questions
How many parsecs is 1 a.u. of length?
How do I convert a.u. of length to parsecs?
How do I convert parsecs back to a.u. of length?
How many parsecs is 100 a.u. of length?
Popular length unit conversions
Convert A.u. of Length to other length units
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Metric / SI (4 units)
Imperial / US Customary (4 units)
Astronomical (8 units)
Sources & references
Conversion factor (1 a.u. = 1.714947e-27 pc) 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.