Overview
What Is a Week Number Calculator?
This tool finds the ISO 8601 week number for any given date, useful for business planning and scheduling.
Find the week number of any date instantly.
This tool finds the ISO 8601 week number for any given date, useful for business planning and scheduling.
Useful for project planning, payroll periods, and any scheduling system that references week numbers.
Input the date you want the week number for.
The result updates automatically.
A standardized system where Week 1 is the week containing the year's first Thursday, with weeks starting Monday.
Because 52 weeks only account for 364 days, and most years have 365 or 366 days, requiring an extra partial week.
No, some regions and systems use different conventions - this calculator uses the common ISO 8601 standard.
Monday, according to the ISO 8601 standard.
Yes, many business and project management systems reference week numbers for scheduling and reporting.
Yes, the last days of December sometimes fall in Week 1 of the following year, or January dates can be in the final week of the prior year.
No, calculations happen entirely in your browser.
Yes, this calculates the ISO week number for any valid date.
Payroll periods, project sprints, and manufacturing schedules often reference week numbers.
Yes, completely free with no sign-up required.