What week is a date in?
Find the ISO week number and Monday-to-Sunday date range.
Find the ISO week
Enter or select values to calculate a result.
How the tool works
Select a date to see its ISO week-year and Monday-to-Sunday range.
Week-year boundaries
The first or last days of a calendar year can belong to an adjacent ISO year.
Weeks guides
Current week number
Find this week's ISO number and week-year.
ISO week dates explained
Read dates written as week-year, week number and weekday.
Start and end of a week
Calculate the Monday and Sunday surrounding a date.
How many weeks are in a year?
Understand why ISO years contain 52 or 53 weeks.
When does week 53 occur?
Identify ISO years with an additional numbered week.
Weeks between two dates
Measure a date interval in complete or fractional weeks.