WEEKS

Returns the number of weeks between two dates.

Syntax:

WEEKS(startdate, enddate, mode)

If mode is 0, WEEKS returns the number of whole weeks between startdate and enddate - that is INT(number_of_days_difference / 7). If mode is 1, WEEKS identifies the Monday_to_Sunday week that startdate and enddate each lie in, and returns the difference between those weeks. If startdate is after enddate the result will be negative.

Example:

WEEKS("2010-05-03", "2010-05-17", 0)

returns 2. Both dates are Mondays, and there are 14 days between them.

WEEKS("2010-05-04", "2010-05-27", 0)

returns 3; there are 23 days between the two dates.

WEEKS("2010-05-06", "2010-05-17", 1)

returns 2; 6 May 2010 lies in week 3-9 May, and 17 May 2010 lies in week 17-23 May, two weeks later.

WEEKS("2010-05-09", "2010-05-10", 1)

returns 1. 9 May 2010 is a Sunday and 10 May 2010 is the Monday of the following week.

Application:

Tracking Project Duration

A project manager at a software company wants to track the duration of different development sprints in weeks. The WEEKS function is a great way to quickly calculate the number of full weeks between a start and end date.

Scenario:

The project manager, Sarah, is reviewing the schedule for three upcoming software development sprints. She has the start and end dates for each sprint and needs to calculate the duration of each in weeks to report to her stakeholders.

The WEEKS Function:

The syntax for the WEEKS function is typically: WEEKS(start_date, end_date). This function calculates the number of full weeks between the two dates.

Table:

Below is the table Sarah created in her spreadsheet to track the sprints and the calculated duration.

	Sprint Name	Start Date	End Date	Duration (Weeks)
	A	B	C	D
1	Login Module	9/1/2025	9/29/2025	4
2	Search & Filter	10/6/2025	11/17/2025	6
3	User Profile	11/24/2025	12/19/2025	3

Explanation of the Results:

Sprint 1: Login Module
- Start Date: September 1, 2025
- End Date: September 29, 2025
- The WEEKS function counts four full weeks between these dates. The last day of the fourth week is September 29th, so it correctly returns 4.
Sprint 2: Search & Filter
- Start Date: October 6, 2025
- End Date: November 17, 2025
- This sprint spans six full weeks. The WEEKS function calculates this duration precisely, returning 6.
Sprint 3: User Profile
- Start Date: November 24, 2025
- End Date: December 19, 2025
- This sprint's duration is 25 days. The WEEKS function only counts full weeks. Since 25 days is equal to 3 weeks and 4 days, the function returns 3, as the fourth week is not fully completed.