Day of Year Calculator
Pick a date and the January 1st of that same year to find which numbered day of the year it is.
Day of Year Calculator
Find which day number (1–365 or 366) a given date falls on within its year.
This calculator provides an estimate for general informational purposes only. It is not a substitute for professional financial, mechanical or engineering advice.
The day-of-year number counts sequentially from January 1st (day 1) through December 31st (day 365 or 366 in a leap year), found here by taking the day difference between your date and that year's January 1st.
Example
- With the default values shown above, this calculator returns: Day Number of the Year ≈ 291.
Frequently Asked Questions
What is 'day of year' used for?
Day-of-year numbering (also called ordinal date) is used in programming, manufacturing date codes, agriculture and scheduling systems that reference a numbered day rather than a calendar date.
Why do I need to enter January 1st separately?
The calculator finds the day number by counting days since the start of the year, so it needs both dates to compute the difference.