The first date after February in a leap year
March 1, 2024 is day 61: January contributes 31 days and February contributes 29. Its ordinal representation is 2024-061, and 305 dates follow it in the year.
Friday, March 1, 2024
2024-061ISO ordinal date
305Days remaining after this date
16.7%Dates reached in the year
January 1 is day 1. Progress counts the entire selected date; it is not a live clock.
Calculations run in your browser. Dates and settings are not uploaded by this tool.
How to use the Day of Year Calculator
- 01
Select Calendar date to find a date’s ordinal number, or Day of year to work in reverse.
- 02
Enter a complete date, or a year and a day number starting at 1. Day 366 is accepted only in a leap year.
- 03
Review the calendar date, YYYY-DDD notation, and year-progress indicator. Copy the result with its counting convention.
Examples
The same ordinal can identify different dates
Day 60 of 2024 is February 29. Day 60 of 1900 is March 1 because 1900 is a common year. Supplying the year is essential for a reliable reverse conversion.
Ordinal dates count from January 1
The first date of a year is day 1, not day 0. The last is day 365 or 366. ISO ordinal notation keeps a four-digit year and a three-digit day number, so January 9, 2026 is 2026-009. The padding helps preserve a consistent format when sorting or exchanging date labels.
Days remaining excludes the selected date
The remaining count is the year’s length minus the selected day number. It reaches zero on December 31. The progress bar, by contrast, includes the entire selected calendar date: January 1 counts as one date reached. It does not measure elapsed seconds or the fraction of today that has passed, and changing your computer’s clock does not change a fixed selected date.
A day-of-year number is not an astronomical Julian date
Some operational systems informally call YYYY-DDD a Julian date. This tool produces a calendar ordinal, reset every January 1. It does not calculate the continuously numbered astronomical Julian Date, Modified Julian Date, or the date in the Julian calendar. Confirm the expected representation before transferring a number into another system.
Common questions
Why is day 366 rejected for my year?
Only leap years have 366 calendar dates. Gregorian century exceptions are checked, so 2000 accepts day 366 while 1900 and 2100 do not.
Do time zones affect the conversion?
A selected calendar date has one ordinal number regardless of time zone. If you start with a timestamp, first decide which location’s calendar date you mean.
How do I convert back?
Choose Day of year, enter the year and the number, and read the resulting YYYY-MM-DD date. Values outside that year are rejected rather than carried into another year.