What Day of the Year Is It? Day of the Year Calculator

Try an example

• The first Moon landing (July 20, 1969): day 201 of the year, in ISO week 29.
• The next leap day (February 29, 2028): day 60. In a common year day 60 is March 1.
• New Year's Day 2027: day 1 of 2027, but in ISO week 53 of 2026, because that week's Thursday is December 31.
• Programmers' Day (day 256, the number of values in a byte): Sunday, September 13 in 2026, and September 12 in a leap year such as 2028.

How the day of the year is worked out

The day number is the count of days from January 1, which is day 1, to the date. December 31 is day 365, or day 366 in a leap year. The calculator also counts the days left after the date, and how much of the year has gone by the end of it.

It uses the Gregorian calendar for every year from AD 1 to 9999, so a leap year is any year divisible by 4, except century years, which must be divisible by 400. 2000 was a leap year; 1900 was not, and 2100 will not be.

Day numbers for the first of each month

To find a day number by hand, take the number for the first of the month and add the day of the month minus one. October 28 in a common year is 274 + 27 = 301.

Day of the year calendar for 2026

Each date in 2026 is shown with its day number out of 365 underneath it. 2026 is a common year; in a leap year such as 2028, every date from March 1 on is one higher. Weeks start on Sunday.

ISO week numbers and US week numbers

Two week-numbering systems are in wide use, and they disagree for part of most years, which is why two websites can give you different answers to "what week is it".

The ISO 8601 standard, used across Europe and in most business and software calendars, starts each week on Monday. Week 1 is the week that holds the year's first Thursday (so it always holds January 4). The days of early January before that week belong to the last week of the previous year, and the last days of December can fall in week 1 of the next. A year has 53 ISO weeks when it starts on a Thursday, or on a Wednesday in a leap year: 71 years in every 400, including 2020, 2026 and 2032.

Calendars in the United States usually start the week on Sunday and call the week with January 1 in it week 1, however few days of it are in January. That is also what Excel's WEEKNUM function returns unless you tell it otherwise (ISOWEEKNUM gives the ISO week). Under this system the last days of December can be week 53, or week 54 in a leap year that starts on a Saturday, as 2000 did and 2028 will.

How many days and weeks are in a year?

A common year has 365 days, which is 52 weeks and 1 day. A leap year has 366 days, 52 weeks and 2 days. That extra day or two is why a date moves one weekday later each year, or two after a leap day. Every year has four quarters: January to March, April to June, July to September and October to December.

Day numbers called Julian dates

Food packaging, factories, the military and some software write a date as the year and the day number, such as 26301 or 2026-301 for October 28, 2026 (the ISO 8601 standard calls this an ordinal date). People often call it a Julian date, though it has nothing to do with the Julian calendar or with the Julian Day Number astronomers use, which counts days continuously from 4713 BC.

Related tools

To find the weekday of any date, BC or AD, use the day of the week calculator. To find the date halfway between two dates, use the date midpoint calculator. To see what century a year is in, use the century calculator. To find the date 90 days from today, or any other count, use the days from today calculator. To check whether a year is a leap year, or when the next one is, use the leap year calculator.

Seeing the year at a glance

A day number tells you where one date sits in the year. To see a whole year of deadlines, trips or milestones side by side, Preceden can put them on a timeline.