Which ordinal day of the year (1 through 365, or 366 in a leap year) a given date falls on.
How it works
The number of days between January 1st of that year and the entered date is counted, plus one, using UTC-based date arithmetic so daylight-saving-time shifts never affect the count.
What this does not include
This does not include the weekday name — for that, use this site’s day-of-week calculator instead. This tool reports the ordinal day number, not the day name.
How to use this calculator
- Enter a date.
A worked example
January 1, 2026: day 1 of the year.
December 31, 2026 (a non-leap year): day 365, with 0 days remaining.
December 31, 2024 (a leap year): day 366 — one extra day from February 29.
What the variables mean
| Variable | Meaning |
|---|---|
| Date | Any calendar date |
| Day of year | How many days into the year that date falls |
Edge cases worth knowing
A leap year shifts every date after February by one day’s worth of numbering — December 31 lands on day 366 in a leap year instead of the usual 365, exactly matching this site’s separate leap year calculator’s logic.
A missing date makes the calculation impossible, so the calculator declines to show a result without one.
Frequently asked questions
Why does a leap year change the total?
A leap year has 366 days instead of 365, since February gains an extra day, so late-year dates shift by one in the day-of-year count during a leap year.
Is this the same as the astronomical “Julian day”?
No — true Julian day is a continuous count of days since a fixed historical epoch used in astronomy; “day of the year” here refers to the everyday, non-astronomical sense of counting days within a single calendar year.
What’s a practical use for this?
Programming and data systems that reference dates by day-of-year number, and tracking progress through the calendar year.
