Week Number Calculator
Find the week number of the year for any date instantly. This tool is useful for payroll, reporting, accounting, project schedules, and business planning.
Result
Week number and calendar details for your selected date.
Week number
16
ISO year
2026
Day of year
108
Weekday
Saturday
Selected date: 18 April 2026
Month: April
Week range: 13 April 2026 to 19 April 2026
Helpful notes
- This calculator uses ISO week numbering where weeks start on Monday.
- Week 1 is the week that contains the first Thursday of the year.
- Useful for payroll, finance, schedules, sprint planning, and reporting.
What does this tool calculate?
It calculates the week number for a selected date and also shows the weekday, month, year day number, and week range.
Common use cases
Use it for payroll cycles, project tracking, operational reporting, audit references, team planning, and deadline coordination.