Julian Date Converter
A Julian date can mean a few things. This page shows the year and day-of-year form, the plain day of the year, and the Julian day number used in astronomy.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
The day of the year counts from January 1 as day 1. The year and day form puts the four-digit year in front of that day number, with the day padded to three digits.
The Julian day number is a running count of whole days from a fixed start point far in the past. It uses a standard integer formula on the year, month and day, and it works for any date in the Gregorian calendar.
Worked example
2026-11-05 is day 309 of the year. In year and day form it is 2,026,309, and its Julian day number is 2,461,350.
Questions
Which Julian date do most people mean?
Many people mean the year and day form. Check which one a form or a system asks for before you enter it.
Is this the Julian calendar?
No. It uses the Gregorian calendar that most of the world uses today, with a standard formula for the day number.
Why do astronomers use a day number?
A single running count of days makes it easy to measure the time between two events, because you only subtract one number from another.
More like this
- Hijri Date ConverterGregorian date to the Islamic (Hijri) calendar.
- Add Days to Date CalculatorMove a date forward or back by days, weeks, months or years.
- Time Unit ConverterSeconds, minutes, decimal hours, days and weeks.
- Military Time Converter24-hour clock to 12-hour clock with AM and PM.
- Date CalculatorAdd or subtract years, months, weeks and days.
- Temperature ConverterCelsius, Fahrenheit and Kelvin.