How to Show Week Numbers in Outlook Calendar (2026)
Week numbers (1–52) are essential if your team plans by “week 23.” Outlook can display them down the left edge of the calendar, and you can set whether the year starts on Jan 1, the first 4-day week (ISO), or the first full week.
1. Show Week Numbers (Classic Outlook for Windows)
- Go to File > Options > Calendar.
- Under Display options, check Show week numbers in the month view and in the Date Navigator.
- (Optional) Set First week of year — choose Starts on Jan 1, First 4-day week, or First full week.
- Click OK.
Week numbers now appear in Month view and in the small Date Navigator.
2. Show Week Numbers (New Outlook for Windows)
- Click the Settings gear (top right).
- Go to Calendar > View.
- Turn on Show week numbers.
- Set First day of week and First week of year as needed.
The numbers appear along the left side of the calendar grid.
3. Show Week Numbers (Outlook on the Web)
- Open the Calendar and click the Settings gear.
- Choose Calendar > View (or Calendar appearance).
- Enable Show week numbers.
- Adjust First week of year if your organization uses ISO weeks.
4. Week Numbers on Outlook Mobile
The Outlook mobile apps don’t expose a week-number toggle. If you need them on the go, use Outlook on the web from your phone’s browser, or check the same shared calendar on a desktop client.
5. Troubleshooting
Week numbers don’t appear in Week or Day view
Classic Outlook only shows them in Month view and the Date Navigator, not Day/Week view. New Outlook and the web show them in more views.
The numbers don’t match my country’s standard
Set First week of year to First 4-day week for the ISO 8601 standard used across most of Europe. “Starts on Jan 1” can produce different numbering.
The option is greyed out or missing
Confirm you’re in the Calendar settings (not Mail) and that you’re on a current build. Update Outlook if the toggle isn’t present.
Related Outlook guides: How to set your working hours in Outlook calendar · How to color code your Outlook calendar · How to add time zones to Outlook calendar · How to share your Outlook calendar · How to create a calendar event in Outlook
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