Julian Date Converter

Free Julian date converter. Convert between Julian day numbers and Gregorian dates. Essential for astronomy and historical research.

Convert between Julian Day Numbers and standard calendar dates. Julian dates are used in astronomy, historical research, and computing for unambiguous date tracking across long time spans.

Common use cases

  • Astronomers calculating celestial events
  • Historians researching ancient documents
  • Programmers implementing date calculations
  • Archaeologists dating historical findings
  • Space agencies tracking mission timelines

How to use

  1. Enter a Julian Day Number or a calendar date
  2. View the conversion instantly
  3. See additional astronomical data if relevant
  4. Convert fractional Julian dates for precise times
  5. Copy results in your preferred format

FAQ

What is a Julian Day Number?

It's a continuous count of days since the beginning of the Julian Period (January 1, 4713 BC).

Is this the same as the Julian calendar?

No, Julian Day Numbers are different from the Julian calendar. They're a numbering system used in astronomy.

What are Modified Julian Dates?

MJD = JD - 2400000.5, a more compact format commonly used in space and satellite tracking.