Julian Day Converter
Convert a Julian Day Number — the continuous day count used in astronomy — to a calendar date and Unix time.
UTC / GMT
Your local time
ISO 8601
Relative
Unix seconds
Unix milliseconds
Current time updating:
How it works
Conversion: JD = unixDays + 2440587.5, where 2440587.5 is the Julian Day of the Unix epoch.
Enter a value to convert it to a human-readable date, or click Use current time. Conversion is two-way and runs entirely in your browser.
Frequently asked questions
What is a Julian Day?
The Julian Day Number is a continuous count of days (and fractions) since noon Universal Time on 1 January 4713 BC. Astronomers use it to avoid calendar complications.
Is it the same as a Julian calendar date?
No — despite the name, the Julian Day Number is just a running day counter, unrelated to the Julian calendar.