ISO week of 2027 Sep 27 – Oct 3, 2027What week of the year is October 1, 2027?
Week details
Friday, October 1, 2027 falls in ISO week 39 of 2027. That week runs from Monday Monday, September 27, 2027 to Sunday Sunday, October 3, 2027, and it touches September and October. The ISO year 2027 has 52 weeks in total, so this is week 39 of 52, or about 75% of the way through the ISO year. ISO 8601 weeks begin on Monday, and week 1 is the week that contains the first Thursday of the year. Because of that rule, the first days of January can belong to the last week of the previous year and the last days of December can belong to week 1 of the next. Most years have 52 weeks; roughly every five or six years a 53rd week is added to keep the count aligned with the seasons. Schedules in manufacturing, logistics, education and project management are often written in week numbers, for example a delivery in week 39 or a sprint that ends in week 41. The week starts in 362 days, so there is time to plan. Keep in mind that US calendars often start the week on Sunday and use a different rule for week 1, so week numbers can differ between countries. The week before is week 38, and the week after is week 40. The year pages list every week with its date range, and the week-number pages link to each of them. Today is Wednesday, September 30, 2026. That is day 273 of 365 in 2026, in ISO week 40, with 92 days to go before the year ends. The next dates people plan around are Diwali on Saturday, October 10; Columbus Day on Monday, October 12; Halloween on Saturday, October 31. The moon is a Waning Gibbous tonight, with about 81% of its face lit. All of these figures are recalculated when the page loads, so they always describe the day you open it, not the day the page was published. The Gregorian calendar has twelve months of 28 to 31 days. A normal year has 365 days and a leap year has 366, with the extra day added to February in every year divisible by four except century years that are not divisible by 400. Because 365 is one more than 52 weeks, most dates move forward one weekday each year and two after a leap day. Weeks are numbered under ISO 8601, which starts weeks on Monday and gives week 1 to the week containing the first Thursday of January.Which week is it?
How ISO week numbers work
Planning by week
Nearby weeks
Today's date at a glance
How the calendar works
ISO week 39 of 2027. On Monday, Monday, September 27, 2027. On Sunday, Sunday, October 3, 2027. 52 ISO weeks. Monday. The week containing the first Thursday of the year. Yes, when January 1 to 3 fall before the first Thursday. The 1st week of the month, counting by seven-day blocks from the 1st. Quarter 4. Friday. Not necessarily; many US calendars start weeks on Sunday and count differently. 362 days. Week 38. Yes. Use the form above.Frequently asked questions
What week number is October 1, 2027?
When does week 39 of 2027 start?
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Can a date in January belong to the previous year's week?
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Is it the same week number in the US?
How many days until the week starts?
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