Day of the year
Every date has an ordinal number: February 1 is day 32, and December 31 is day 365 (or 366 in a leap year). The calculator defaults to today and shows the day number, the days remaining in the year, and the ISO week. Day-of-year numbers (sometimes called Julian dates in aviation, agriculture, and manufacturing date codes, though that name properly belongs to an astronomy count) are how sequential day math avoids month-length headaches.
Common questions
- Is the day of the year the same as a Julian date?
- Colloquially, yes: packaging codes and military/aviation formats like 2026-229 use “Julian date” to mean the day-of-year ordinal. Strictly, no: the astronomical Julian Day is a continuous count of days since 4713 BC. This page computes the ordinal.
- How do I get the day of year in code?
- Python: date.timetuple().tm_yday. PostgreSQL: EXTRACT(DOY FROM date). Java: LocalDate.getDayOfYear(). strftime uses %j.
- When does the day number reach 366?
- Only in leap years, next in 2028. In a leap year every date from March 1 onward has a day number one higher than in a common year, which is the off-by-one that breaks naive day-of-year arithmetic.