Julian Date Calculator

"Julian date" means two different things. This page gives both: the astronomers’ Julian Day Number and the day-of-year code (like 26266) used on product labels and in the military.

What Do You Want to Find?
Enter YYDDD (5 digits), YYYYDDD (7 digits), or a Julian Day Number like 2461307.
Dates use your browser’s date picker.
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Julian date
Julian Day Number (noon UTC)
Modified Julian Date
Ordinal date (YYDDD)
Ordinal date (YYYYDDD)
Calendar date
Work

Saved Calculations

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Two Kinds of Julian Date

Ordinal date (YYDDD): the last two digits of the year followed by the day of the year, 001 to 365 (366 in leap years). It’s used on food and drug lot codes and in military logistics.

Julian Day Number (JDN): a continuous day count used in astronomy. Day 0 began at noon UTC on January 1, 4713 BC (Julian calendar). The Modified Julian Date is JD − 2,400,000.5 and starts at midnight.

JDN = days since 1970-01-01 + 2,440,588   MJD = JDN − 2,400,001 at midnight

Worked Example

Tips

Two-digit years 00–68 are read as 2000–2068 and 69–99 as 1969–1999. Check which kind of Julian date your label or software expects.