Time & Dates

What Is the Day of the Year?

The day of the year, or ordinal date, is a date's position counted from January 1, which is day 1. December 31 is day 365, or day 366 in a leap year. It is used in scheduling, manufacturing codes, and science, and in ISO 8601 it can be written as YYYY-DDD, such as 2026-270.

Days Remaining

Days left in the year = total days in the year − day of the year.

Example

September 27, 2026 is day 270 of the year: January through August contain 243 days in a non-leap year, plus 27 days in September. In a leap year, every date from March 1 onward is one day number higher.

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📆 Week Number Calculator ISO 8601 and US week numbers for any date, and the dates of any week. Calculate → 📅 Date Calculator Find days between two dates, or add/subtract days from a date. Calculate →

🔗 Related Terms

Leap Year ISO Week Number ISO 8601 Date Format

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Last updated: September 27, 2026. This definition is for general educational purposes only. It is not financial, investment, tax, legal, or medical advice, and it does not recommend any product or course of action. For decisions about your own situation, consult a qualified professional.