Parsec Calculator

How to Use This Calculator

1. Enter the parallax angle in arcseconds to get distance in parsecs and light-years.
2. Use From Distance tab to find the parallax for a known distance.
3. Use Stellar Catalog tab for pre-loaded Hipparcos/Gaia values.
4. Professional tier adds distance modulus, parallax error propagation, and kiloparsec scaling.

Formula

Example

Frequently Asked Questions

• What is a parsec? ▼
  A parsec (pc) is the distance at which 1 Astronomical Unit (AU) subtends a parallax angle of 1 arcsecond. It equals approximately 3.0857×10¹⁶ m, 3.2616 light-years, or 206,265 AU.
• How do you calculate distance from parallax? ▼
  For parallax angle p in arcseconds, distance d = 1/p parsecs. For example, Sirius has p = 0.3792 arcsec, so d = 1/0.3792 ≈ 2.637 pc = 8.60 ly.
• What is the distance modulus? ▼
  The distance modulus is μ = m − M = 5 log₁₀(d_pc) − 5, where m is apparent magnitude and M is absolute magnitude. It converts between the two using known distance in parsecs.
• How accurate is parallax for measuring distances? ▼
  Ground-based telescopes can measure parallax reliably to ~100 pc. The Hipparcos satellite measured to ~1 kpc with ~1 mas accuracy. Gaia (ESA) achieves ~20 microarcsecond precision, enabling distances to ~10 kpc.
• What is Gaia's parallax precision? ▼
  Gaia DR3 achieves ~10–20 microarcsecond parallax precision for bright stars (G<12), enabling distance measurements to ~10 kpc for millions of stars. This is a 100× improvement over Hipparcos.

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