Week 21 2026: May 18–24, 2026
Week 21 starts on Monday, May 18, 2026 and ends on Sunday, May 24, 2026.
Quick answer
Week 21 of 2026 is the seven-day ISO week from May 18, 2026 to May 24, 2026. ISO weeks always run from Monday to Sunday.
Use week 21 in professional planning
This permanent week reference can be used in project plans, payroll notes, weekly reports, production schedules and deadline documents. Share the week number together with the ISO year and exact date range to avoid ambiguity around New Year.
For calculations that span more than one week, use the weeks between dates calculator. For work schedules, compare the same range with the business days calculator or open the project timeline calculator.
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FAQ
What are the dates for week 21 of 2026?
The dates are May 18, 2026 through May 24, 2026.
What day does this week start?
It starts on Monday.
What day does this week end?
It ends on Sunday.
How should I write this week in a report?
Use “ISO week 21 of 2026 (May 18–May 24, 2026)” so the week-year and date range are both clear.