Day of Year Calculator
Enter a Gregorian date and calculate its day-of-year number, whether the year is a leap year, total days in the year, and days remaining.
Use this browser-local calculator for annual progress checks, schedules, log dates, content calendars, and day-of-year fields in data workflows. The calculation stays in your browser and does not upload the date.
Browser-local calculation
Day of Year Calculator
Day-of-year result
How to use
Finish in three steps
- 01
Choose or enter a Gregorian date in YYYY-MM-DD format.
- 02
Run the calculation to see the day number, year length, leap-year status, and days remaining.
- 03
Before copying the result, confirm that your source system uses the same calendar-day convention.
How day of year is calculated
The calculator treats January 1 as day 1, then counts calendar days from the start of the year to the selected date.
Leap-year impact
Leap years have 366 days. February 29 shifts March 1 and later dates one day higher than they would be in a common year.
Local date boundaries
The input is date-only. The calculation avoids shifting the chosen date across midnight because of local time zones, daylight saving time, or UTC offsets.
FAQ
About this tool
Is January 1 day 0 or day 1?
This tool uses the common 1-based day-of-year convention, so January 1 is day 1.
What day of year is February 29?
In a leap year, February 29 is day 60. Common years do not have February 29.
Does this consider holidays or business days?
No. The result is based on Gregorian calendar days only, not holidays, make-up workdays, company schedules, or regional calendars.
Does the tool upload my date?
No. The calculation runs locally in your browser without an account, backend service, external API, or database.
Keep exploring
Related tools
Last updated: