Day of the Year & Week Numbers
Today's day number and ISO week, plus a day-by-day table of day and week numbers for any year from 1600 to 2400.
| Date | Day number | Days remaining | Days from today | Week number | % of year done | % of year left |
|---|
Other years
1600s to 1980s
1990 to 2040
2050s to 2400s
Look up a date
Date to day number
Day number to date
Day numbers, ISO weeks and leap years
The day of the year, also called the ordinal date, counts the days of a year from 1 January. 1 January is day 1, 1 February is day 32, and 31 December is day 365 in a common year or day 366 in a leap year. Food packaging, warehouse stock and military logistics often print the day number as a short date code, sometimes loosely called a Julian date. Days remaining counts the days after a date until the end of the year, so 31 December always shows 0.
The "% of year done" column divides the day number by the number of days in the year, so 31 December reaches 100%. Day 278 of 2026 gives 76.2% done and 23.8% left. The today panel uses the same figures.
ISO 8601 week numbers
ISO 8601 weeks start on Monday and end on Sunday. Week 1 is the week holding the first Thursday of the year, which is also the week containing 4 January. A year has 52 or 53 ISO weeks as a result. Years starting on a Thursday get 53 weeks, and so do leap years starting on a Wednesday, so 2026 has 53 weeks and 2027 has 52.
Dates around New Year often belong to a week of the neighbouring year. 31 December 2024 falls in week 1 of 2025, written 2025-W01, and 3 January 2021 falls in week 53 of 2020. The table shows the week-year in small print next to such week numbers. The United States and Canada usually number weeks from Sunday, with week 1 holding 1 January, so a calendar printed there often shows a different week number for the same date.
Leap years
A leap year has 366 days, with 29 February as day 60. Every year divisible by 4 is a leap year, except century years, which also need to be divisible by 400. 2000 was a leap year, while 1900 was not and 2100 will not be either. The table applies the Gregorian rules to every year from 1600 to 2400. Britain and its colonies switched from the Julian calendar in 1752, so British records from before the switch differ from the table by 10 or 11 days.
ISO ordinal dates
ISO 8601 also defines an ordinal date format: the year, a hyphen and the three-digit day number. Day 278 of 2026 is written 2026-278, and 1 January 2026 is 2026-001. The compact form drops the hyphen and gives 2026278. The ISO week date format adds the weekday to the week, counting Monday as 1, so Monday 5 October 2026 is 2026-W41-1.
All counts use whole calendar dates in UTC, so a daylight saving change never shifts a day number. Today follows the date on the device clock and moves on at local midnight. Year links use the address minitool.app/day-of-year/?year=2027, ready to bookmark or share.