Convert Millimeter to Parsec
Convert millimeters to parsecs instantly. 1 millimeter = 3.240779e-20 parsec — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Parsec to Millimeter converter for the reverse conversion.
Units explained
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
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 to Parsec conversion formula
The relationship between millimeters and parsecs:
To convert millimeters to parsecs, multiply the value in millimeters by 3.240779e-20. To reverse, multiply parsecs by 3.085678e+19.
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 Millimeter converter for the reverse direction.
Step-by-step: convert millimeters to parsecs
- Write down the value in millimeters (mm).
- Multiply that value by the factor 3.240779e-20.
- The product is the equivalent value in parsecs (pc).
- To reverse, multiply the parsec value by 3.085678e+19.
Worked examples
Example 1 — Convert 1 mm to pc:
1 × 3.240779e-20 = 3.240779e-20 pc
Example 2 — Convert 100 mm to pc:
100 × 3.240779e-20 = 3.240779e-18 pc
Real-world example — Ruler-scale measurements
A 30-millimeter school ruler converts cleanly to parsecs — useful when buying a desk accessory from a retailer whose product specs use a different unit.
30 mm × 3.240779e-20 = 9.722338e-19 pc
Real-world example — Hardware-scale dimensions
A 10-millimeter fastener or component is about as long as a thumbnail. Mechanics and DIY enthusiasts convert between millimeters and parsecs daily when mixing metric and imperial tools.
10 mm × 3.240779e-20 = 3.240779e-19 pc
Real-world example — Postcard and small-object dimensions
A postcard is about 5 millimeters wide. Converting to parsecs is essential for international postal addressing forms that ask for dimensions in different units across countries.
5 mm × 3.240779e-20 = 1.62039e-19 pc
Millimeter to Parsec conversion table
Standard reference values for converting millimeters to parsecs:
| Millimeter [mm] | Parsec [pc] |
|---|---|
| 0.01 | 3.240779e-22 |
| 0.1 | 3.240779e-21 |
| 1 | 3.240779e-20 |
| 2 | 6.481559e-20 |
| 3 | 9.722338e-20 |
| 4 | 1.296312e-19 |
| 5 | 1.62039e-19 |
| 10 | 3.240779e-19 |
| 20 | 6.481559e-19 |
| 30 | 9.722338e-19 |
| 40 | 1.296312e-18 |
| 50 | 1.62039e-18 |
| 100 | 3.240779e-18 |
| 500 | 1.62039e-17 |
| 1000 | 3.240779e-17 |
Frequently asked questions
How many parsecs is 1 millimeter?
How do I convert millimeters to parsecs?
How do I convert parsecs back to millimeters?
How many parsecs is 100 millimeters?
Popular length unit conversions
Convert Millimeter to other length units
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Metric / SI (17 units)
Imperial / US Customary (27 units)
Nautical (1 units)
Astronomical (9 units)
Atomic / Physics (6 units)
Typographic (3 units)
Sources & references
Conversion factor (1 mm = 3.240779e-20 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.