Weeks of the Year Calculator – Find Week Number & Calculate Future Dates

Total Weeks in Year
Current Week #
Weeks Remaining

The date 1 week(s) from your selected date will be:

This calculator determines the week number of a selected date within its year, the total number of weeks in that year, and the weeks remaining. It also allows you to project a future date by adding a specified number of weeks.

Calculation Method

The calculator adheres to the ISO 8601 standard for determining the week number. In this system, a week starts on Monday, and the first week of the year is the one that contains the first Thursday. A year can have either 52 or 53 weeks based on this standard.

To find a future date, the calculator uses a straightforward formula.

Future Date = Start Date + (Number of Weeks × 7 days)

Calculation Examples

Start Date Weeks to Add Resulting Future Date Week # of Start Date
January 15, 2024 5 February 19, 2024 3
July 4, 2024 10 September 12, 2024 27
December 25, 2025 2 January 8, 2026 52
February 29, 2024 15 June 13, 2024 9
January 1, 2026 1 January 8, 2026 1
December 31, 2024 3 January 21, 2025 1 (of 2025)
October 10, 2026 8 December 5, 2026 41
May 20, 2025 20 October 7, 2025 21
March 1, 2024 52 February 28, 2025 9
September 20, 2025 0 September 20, 2025 38