Julian Date Converter
Convert between Julian Date (JD), Modified Julian Date (MJD), and standard date/time formats accurately.Julian Date (JD / MJD)
Local Date & Time
How to Use
- 1To convert a Julian Date to a calendar date, enter the JD value (e.g. 2460200.5) in the Julian Date field and click 'Convert to Date'.
- 2To convert a calendar date to Julian Date, select the date and time using the date picker, then click 'Convert to Julian'.
- 3Click 'Current Time' to instantly populate both fields with the current moment's Julian Date and calendar date.
- 4All results include the Julian Date (JD), Modified Julian Date (MJD), UTC time, and your local time.
- 5Use the copy buttons next to each result to copy the value to your clipboard.
About Julian Date
What is a Julian Date?
The Julian Date (JD) is a continuous count of days and fractions since noon on January 1, 4713 BC (Julian calendar). It is the standard time format used in astronomy, space science, and software to easily calculate the difference between two dates without calendar arithmetic.
Modified Julian Date (MJD)
The Modified Julian Date (MJD) is defined as JD − 2400000.5. It was introduced to reduce the number of digits in calculations and make timestamps fit in smaller data types. The MJD epoch begins at midnight on November 17, 1858.
Common Applications
Julian Dates are widely used in astronomy to record the timing of observations, in satellite operations, in timekeeping standards like GPS and NTP, and in programming to calculate date differences without dealing with months and leap years.