Skip to main content

Julian Date (JD) Calculator and Calendars

JD Calculator


What is Julian Date?
Compute the JD or UT yourself

To convert from JD to calendar date enter the Julian Date below:


To convert from UT to JD enter the time in UT: 

Year Month Day
Hour Min Sec






This application assumes use of the Gregorian calendar and only works correctly for dates on or after October 15, 1582. For more on Julian Dates, click here.

JD Calendars
AAVSO produced JD Calendars give the last four digits of the Julian Day for each day of every month for a year. The months January-June are on one page while July–December are on the second page. For the complete JD, add 2,450,000 to the four digit value given in the calendar for the Astronomical Day of your observation.
Click on a year in the left column to download a 2-page .pdf version of the calendar for that year. The calendar for the 2016 is shown below. Click on the image to get a bigger version.
Calendars available for download
(in .pdf format):

If you need to download the Acrobat plug-in to read a pdf file, you may download it for free from the Adobe website.

AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484