How to use the Day of Year Calculator
Pick a date to see its day number, from 1 on 1 January up to 365, or 366 in a leap year, on 31 December.
Worked example
In a normal year, 1 March is day 60, because January has 31 days and February has 28. In a leap year such as 2028, 1 March is day 61. The last day of the year is 365 in a normal year and 366 in a leap year.
Where day numbers are used
Day numbers, also called ordinal dates, show up in batch and lot codes on food and medicine, in shipping and logistics systems, in astronomy and in date formats such as 2026-060. They make it easy to count how far into the year you are.
How it works
Days elapsed since January 1 plus one.
Examples
- 9 November 2026
Day of year: 313
- 31 December 2026
Day of year: 365
- 1 March 2028 (a leap year)
Day of year: 61
Limitations and assumptions
Uses the Gregorian calendar. Leap years add 29 February, which moves every later date in that year up by one.
Frequently asked questions
How is the day of year calculated?
Count the days in the earlier months, then add the day of the month.
How many days are in a year?
365, or 366 in a leap year.
Does leap year change the numbering?
Yes, dates after 28 February shift by one in a leap year.
Where is it used?
In logistics, manufacturing batch codes and scientific data.