Athena Kits

Julian Date Converter

"Julian date" means two different things. In manufacturing, food labelling and the military it usually means the day of the year (an ordinal date such as 26308 for November 4, 2026). In astronomy it means the Julian Day Number, a running count of days since 4713 BC. This converter shows both.

Calendar date to Julian date

Julian date to calendar date

Formats explained

FormatExample for Nov 4, 2026Used in
YYDDD26308Food and pharmaceutical lot codes, military
YYYYDDD2026308Mainframe systems, data files (ISO 8601 ordinal date 2026-308)
Julian Day Number2461349Astronomy, date arithmetic in software

A 5-digit YYDDD code does not say which century it belongs to. The converter assumes the years 2000–2099. Seven-digit numbers that start with 24 or 25 and do not fit YYYYDDD are read as Julian Day Numbers.

Julian date calendar 2026

Day-of-year number for every date in 2026. Find the month across the top and the day down the side. Add the two-digit year in front for the YYDDD form (for example 26045 is February 14, 2026).

DayJanFebMarAprMayJunJulAugSepOctNovDec
1001032060091121152182213244274305335
2002033061092122153183214245275306336
3003034062093123154184215246276307337
4004035063094124155185216247277308338
5005036064095125156186217248278309339
6006037065096126157187218249279310340
7007038066097127158188219250280311341
8008039067098128159189220251281312342
9009040068099129160190221252282313343
10010041069100130161191222253283314344
11011042070101131162192223254284315345
12012043071102132163193224255285316346
13013044072103133164194225256286317347
14014045073104134165195226257287318348
15015046074105135166196227258288319349
16016047075106136167197228259289320350
17017048076107137168198229260290321351
18018049077108138169199230261291322352
19019050078109139170200231262292323353
20020051079110140171201232263293324354
21021052080111141172202233264294325355
22022053081112142173203234265295326356
23023054082113143174204235266296327357
24024055083114144175205236267297328358
25025056084115145176206237268298329359
26026057085116146177207238269299330360
27027058086117147178208239270300331361
28028059087118148179209240271301332362
29029088119149180210241272302333363
30030089120150181211242273303334364
31031090151212243304365

The Julian Day Number shown is for noon UTC on the given date. Astronomers count each Julian day from noon, so the fractional Julian Date at midnight is the number minus 0.5.