What Week: Week 51
Find the calendar dates covered by any ISO week number.
ISO Week 51 of 2026 runs from December 14 to December 20, 2026, with roughly 1 ISO weeks remaining in the year after it. ISO 8601 weeks always run Monday through Sunday and belong to the year containing that week's Thursday, which is why the first few days of January sometimes belong to the final week of the previous year. No major U.S. holidays tracked by Dayswise fall within this specific week in 2026. Next year, 2027, the same week number runs from December 20 to December 26, 2027 instead, since the exact dates shift slightly every year.
As of October 1, 2026, 12:19 PM (America/New York).
Position in the Year
Week 51 falls in the second half of the year, roughly 98% of the way through 2026's 52-53 ISO weeks.
Quarter Overlap
This week sits in calendar Q4, based on its Monday (December 14).