How to use it
The page opens on today’s date and shows which week of the year it is, which day of the year, how many days are left, and which quarter you are in. Choose any other date to see the same facts for it. To go the other way, type a year and a week number into Find the dates of a week to see the Monday and Sunday that week starts and ends on, which is handy for planning, timesheets and delivery dates quoted as “week 42”.
Which week numbering?
Two systems are in common use, and they can give different answers. The ISO week (used across Europe, in most business calendars and in the ISO 8601 standard) starts on Monday, and week 1 is the week that contains the year’s first Thursday, which is the same as the week with 4 January. That means 29 to 31 December can be in week 1 of the next year, and 1 to 3 January can be in week 52 or 53 of the last. The US week starts on Sunday, and week 1 is the week with 1 January, so it can be a short week. Both are shown. Years have 52 or 53 ISO weeks.
Questions
How many weeks are in a year? 52 or 53 ISO weeks; a year has 53 when it starts on a Thursday, or on a Wednesday in a leap year. Does it use my time zone? Today’s date comes from your device, and the sums use whole calendar days, so daylight saving never changes the result. Why does it only go back to 1583? The Gregorian calendar began in 1582, and earlier dates differ by country. To print a calendar with week numbers, use the Printable Calendar.