This day of year calculator tells you the ordinal day number for any date. The day number counts how many days have passed since the first of January, where January 1 is day 1 and December 31 is day 365 or day 366 in a leap year.
For example, June 22, 2026 is day 173 of 2026, with 192 days left in the year.
How the Day Number Works
The day of the year, sometimes called the ordinal date or Julian day in everyday use, is a single number that represents a date inside one year. It is widely used in spreadsheets, science, logistics, and software.
- January 1 is always day 1.
- In a common year, December 31 is day 365.
- In a leap year, an extra day on February 29 makes December 31 day 366.
Leap Years and the Total
A year has 366 days when it is divisible by four, except for century years that are not divisible by four hundred. The calculator checks this automatically, so the total and the remaining count are always correct.
What People Use It For
- Filling in day of year fields in spreadsheets and forms
- Tracking progress through the year
- Planning around how many days are left
- Working with scientific, shipping, or batch date codes
Common Questions
January 1 is day 1. The count starts at one, not zero.
A leap year has 366 days because February has 29 days instead of 28.