ISO week 2026-W52

Week 52, 2026

Monday, December 21 – Sunday, December 27, 2026

ISO week 52 of 2026 (2026-W52) runs from Monday, December 21, 2026 to Sunday, December 27, 2026.

This week starts 10 weeks from now. The current week is week 42, 2026.

The 7 days of week 52

Dates in week 52, 2026
Day	Date	Day of year	US week	ISO date
Monday	December 21, 2026	355 of 365	52	2026-W52-1
Tuesday	December 22, 2026	356 of 365	52	2026-W52-2
Wednesday	December 23, 2026	357 of 365	52	2026-W52-3
Thursday	December 24, 2026	358 of 365	52	2026-W52-4
Friday	December 25, 2026	359 of 365	52	2026-W52-5
Saturday	December 26, 2026	360 of 365	52	2026-W52-6
Sunday	December 27, 2026	361 of 365	53	2026-W52-7

Week 52 at a glance

ISO code: 2026-W52 (Monday is 2026-W52-1, Sunday is 2026-W52-7)
Month: December
Quarter: Q4 of 2026
Day of year: Days 355–361 of 365
US week number: Monday–Saturday: US week 52; Sunday: US week 53 (Sunday-start weeks, week 1 contains January 1)
Even or odd: Week 52 is an even week
Weeks left: After this week, 1 ISO week remain in 2026 (53 weeks in total)
Year progress: By Sunday, 99% of 2026 has passed

Holidays and key dates

Friday, December 25: Christmas Day – US federal holiday

End of the ISO year

2026 is a long ISO year, so week 52 is not the last week: week 53 follows, from Monday, December 28, 2026.

Week numbers follow ISO 8601: weeks start on Monday and week 1 contains the first Thursday of the year. US weeks start on Sunday, with week 1 containing January 1.

Questions about week 52, 2026

What are the dates of week 52 in 2026?

Week 52 of 2026 starts on Monday, December 21, 2026 and ends on Sunday, December 27, 2026.

What month is week 52 of 2026?

Week 52 falls in December. By the Thursday rule that ISO 8601 uses for years and quarters, it counts as a December week.

How do I get week 52 of 2026 in Excel or Google Sheets?

=ISOWEEKNUM(DATE(2026,12,21)) returns 52. To go the other way, =DATE(2026,1,4)-WEEKDAY(DATE(2026,1,4),2)+1+(52-1)*7 returns the Monday, December 21, 2026.