Convert between Julian Date, Modified Julian Date and normal calendar dates. Astronomical continuous day count, accurate to the second, free tool. All processing runs locally in your browser. Your data is not uploaded to any server.
100% Local Processing
How to Use
Move between the Julian Date used in astronomy and the calendar you read every day. The Modified Julian Date is included as well.
Steps
Enter a Julian Date such as 2460000.5, an MJD, or a normal date.
Set the direction to match what you entered.
Click Convert and read both the JD and the MJD alongside the calendar date.
What a Julian Date is
A continuous count of days since noon Universal Time on 1 January 4713 BC.
The decimal part of a JD is the fraction of the current day.
The Modified Julian Date subtracts 2400000.5, so modern dates are five digits.
JD 2451545.0 is exactly 2000 January 1 at 12:00 UTC.
Features
Both directions are supported from one input box.
Results are given to six decimal places, about one millisecond.
Julian centuries from the J2000 epoch are included for astronomy work.
All processing runs locally in your browser. Your data is not uploaded to any server.