Week Number → Date Converter
Enter a year and an ISO week number to find the exact Monday–Sunday date range for that week.
Project planning tools, payroll systems, and academic calendars often reference specific weeks by number rather than by date range — "submit by end of week 12" — which works fine inside the system that assigned the number but becomes a genuine puzzle the moment you need to translate that into an actual calendar date range to plan around.
This is the reverse problem of the ISO Week Number Calculator: instead of starting with a date and finding its week number, you start with a week number and need to find the specific Monday-through-Sunday range it corresponds to for a given year. The two calculations use the same underlying ISO 8601 rule — since week boundaries shift slightly from year to year depending on which day of the week January 1st falls on — but starting from the number rather than the date means you can't just count forward from memory without risking an off-by-one error.
Enter a year and a week number, and this tool returns the exact date range that week covers, calculated using the same ISO 8601 rules that define week 1 as the week containing the year's first Thursday — the same standard most scheduling and project-management software relies on internally.
- Enter a year.
- Enter an ISO week number (1–53).
- Press Find dates to see that week's date range.
ISO 8601 defines week 1 as the week containing the year's first Thursday, so week 1 can begin a few days before January 1st.
Yes — that tool goes from a date to a week number; this one goes from a week number back to its date range.