- Week 52 of 2015 starts on Sunday, December 20 or Monday December 21.
- Week 1 of 2016 starts on Sunday December 27 or Monday December 28.
- Week 2 of 2016 starts on Sunday January 3 or Monday January 4.
- The last week of the year 2016 is week number 53.
Note The week may start on Sunday or Monday, depending on if you have Sunday or Monday configured as the first day of the week in the Outlook Calendar options.
- The Show week numbers in the month view and in the Date Navigator option is enabled in the Calendar Display options.
- The First day of week option is set to Sunday or Monday in Calendar Work time options.
- The First week of year option is set to Starts on Jan 1 in Calendar Work time options. This is the default option.
- In Outlook, click File, and then click Options.
- Click Calendar.
- Under the Work time section, change the First week of year option to either First 4-day week or First full week, as you prefer.
- Click OK.
Note International Organization for Standardization (ISO) 8601 defines the first week of the year as the week that contains January 4.
Article ID: 3135004 - Last Review: 11 Jan 2016 - Revision: 1