Day of Year Calculator
Find what day number of the year any date falls on.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Day of Year Calculator
Select a date and the calculator instantly shows the ordinal day number, total days in that year, days remaining, and the percentage of the year that has passed.
- Pick a date. Defaults to today. Select any past or future date.
- Read the ordinal number. January 1 is Day 1, December 31 is Day 365 (or 366 in a leap year).
- See the progress. The progress bar and "Year Complete" percentage show where the date falls in the year.
About the Day of Year Calculator
The ordinal date (also called the Julian date in some contexts) is used in astronomy, military systems, databases, and scientific applications where a single integer is more convenient than a month/day representation. ISO 8601 defines the ordinal date as YYYY-DDD, where DDD is the three-digit day number (e.g., 2024-186 for July 4, 2024).
Leap years have 366 days instead of 365. Any date after February 28 in a leap year has an ordinal number that is 1 higher than the same date in a non-leap year. For example, March 1 is Day 60 in a non-leap year and Day 61 in a leap year.
Frequently Asked Questions
What day number is today?
The calculator defaults to today's date, so the result shows today's day number automatically when you first open it. The day number counts from January 1 (Day 1) through December 31 (Day 365 or 366). The result updates if you change the date.
What is day 100 of the year?
Day 100 of the year is April 10 in a non-leap year and April 9 in a leap year. In 2024 (a leap year), day 100 falls on April 9. To find the date for any day number, use the Add / Subtract Date Calculator: start from January 1 and add the day number minus 1.
Does a leap year change the day numbers?
Yes. In a leap year, February 29 is Day 60, and all dates from March 1 onward have day numbers that are 1 higher than in a non-leap year. The total days in the year shows 366 instead of 365, and the percentage calculations adjust accordingly.
What is the difference between the day of year and the Julian date?
The "day of year" or ordinal date is a number from 1 to 365 (or 366) counting days from January 1. The "Julian Date" (JD) used in astronomy is a completely different system: a continuous count of days since January 1, 4713 BC at noon UTC, currently over 2.4 million. The ordinal date format used here is sometimes informally called a Julian date in business contexts, but the astronomical Julian Date is different.