Convert Parsec to Millimeter
Convert parsecs to millimeters instantly. 1 parsec = 3.085678e+19 millimeter — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Millimeter 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.
Millimeter
A millimeter is a metric unit of length equal to one thousandth of a meter (1/1000 m). It is the standard small-scale unit in the SI system and is widely used wherever sub-centimeter precision matters.
The millimeter was defined alongside the meter when France adopted the metric system in 1795, using the standard SI prefix milli- (from Latin mille, "thousand") to denote one-thousandth.
Millimeters are used in engineering drawings, machining, manufacturing, paper sizes, rainfall measurement, and any context where dimensions below one centimeter need to be specified clearly. Most rulers worldwide are marked in millimeters.
Adopted in 1795 in France as part of the original metric system; standardized internationally by the Metre Convention in 1875 and confirmed in the SI in 1960.
Parsec to Millimeter conversion formula
The relationship between parsecs and millimeters:
To convert parsecs to millimeters, multiply the value in parsecs by 3.085678e+19. To reverse, multiply millimeters by 3.240779e-20.
How to use this converter
Type a value into the calculator. The result in millimeters updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Millimeter to Parsec converter for the reverse direction.
Step-by-step: convert parsecs to millimeters
- Write down the value in parsecs (pc).
- Multiply that value by the factor 3.085678e+19.
- The product is the equivalent value in millimeters (mm).
- To reverse, multiply the millimeter value by 3.240779e-20.
Worked examples
Example 1 — Convert 1 pc to mm:
1 × 3.085678e+19 = 3.085678e+19 mm
Example 2 — Convert 100 pc to mm:
100 × 3.085678e+19 = 3.085678e+21 mm
Parsec to Millimeter conversion table
Standard reference values for converting parsecs to millimeters:
| Parsec [pc] | Millimeter [mm] |
|---|---|
| 0.01 | 3.085678e+17 |
| 0.1 | 3.085678e+18 |
| 1 | 3.085678e+19 |
| 2 | 6.171355e+19 |
| 3 | 9.257033e+19 |
| 4 | 1.234271e+20 |
| 5 | 1.542839e+20 |
| 10 | 3.085678e+20 |
| 20 | 6.171355e+20 |
| 30 | 9.257033e+20 |
| 40 | 1.234271e+21 |
| 50 | 1.542839e+21 |
| 100 | 3.085678e+21 |
| 500 | 1.542839e+22 |
| 1000 | 3.085678e+22 |
Frequently asked questions
How many millimeters is 1 parsec?
How do I convert parsecs to millimeters?
How do I convert millimeters back to parsecs?
How many millimeters is 100 parsecs?
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Imperial / US Customary (4 units)
Sources & references
Conversion factor (1 pc = 3.085678e+19 mm) 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.