Convert a Julian Day to a Date

Need to convert Julian Day Numbers (JDN) into readable calendar dates? The Convert a Julian Day to a Date Tool lets you enter one or more Julian Day Numbers and instantly converts each into a YYYY-MM-DD Gregorian date. Whether you’re working in astronomy, history, or software development, this tool makes it easy to translate numerical time values into real-world dates.

It supports bulk entry, file upload, and live results.

Paste your input above or import a file below.
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Supported file types: .txt, .csv, .log
Total lines: 0

How to Use:

  1. Enter one Julian Day Number per line into the Input Julian Day Numbers box.
  2. Or click Choose File to import a .txt, .csv, or .log file with JDN values.
  3. The Converted Dates box will update instantly with formatted calendar dates.
  4. Use Copy Output to copy the result or Export to File to download it.
  5. Click Clear All to reset everything and start over.

What Convert a Julian Day to a Date Tool can do:

  • Converts any valid Julian Day Number (e.g. 2451545) into a YYYY-MM-DD Gregorian date
  • Accepts multiple entries at once
  • Flags invalid lines with clear messages
  • Supports text and file input
  • Includes export and copy functionality
  • Provides a demo output on page load

Example:

Input:

2451545
2460259
2299161
2415021
2460371

Output:

2451545 → 2000-01-01
2460259 → 2023-11-01
2299161 → 1582-10-15
2415021 → 1900-01-01
2460371 → 2024-03-01

Common Use Cases:

This tool is perfect for developers working with date libraries, historians working with ancient records, or astronomers referencing celestial data. It simplifies complex calendar math and instantly gives you readable, exportable results.

Useful Tools & Suggestions:

Need to go the other way? Convert a Date to a Julian Day flips it back cleanly. And for working across calendars, Convert Julian Calendar to Gregorian Calendar helps align everything to modern dates.

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