Week 4 2026: January 19–25, 2026
Week 4 starts on Monday, January 19, 2026 and ends on Sunday, January 25, 2026.
Quick answer
Week 4 of 2026 is the seven-day ISO week from January 19, 2026 to January 25, 2026. ISO weeks always run from Monday to Sunday.
Use week 4 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.
Weeks around week 4
Browse priority week calendars
Continue with a planning tool
FAQ
What are the dates for week 4 of 2026?
The dates are January 19, 2026 through January 25, 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 4 of 2026 (Jan 19–Jan 25, 2026)” so the week-year and date range are both clear.