Show Week Numbers in Google, Outlook & Apple Calendar

Every major calendar app can display week numbers, and every one of them hides the setting somewhere different. None of them turn it on by default in the United States, which is why "let's push it to week 42" often gets blank looks in an American office and instant recognition in a European one, especially in industries that plan around fiscal weeks rather than calendar months.

Here is where each switch lives, followed by the part most guides skip: what to do when two calendars show a different number for the same Monday.

| App | Where the setting lives | Shows up in | | --- | --- | --- | | Google Calendar (web) | Settings > View options > Show week numbers | Month view and the mini calendar | | New Outlook for Windows | View > Calendar settings > Calendar > View | Month view | | Classic Outlook for Windows | File > Options > Calendar > Display options | Month view and the Date Navigator | | Outlook on the web | Settings > Calendar > View | Month view | | Apple Calendar (Mac) | Calendar > Settings > Advanced | Week, Month, and Year view | | Apple Calendar (iPhone, iPad) | Settings > Apps > Calendar > Week Numbers | Month view |

Google Calendar

The option exists only in the browser version, and it applies to your Google account rather than to one device.

1. Open Google Calendar on a computer.
2. Click the gear icon at the top right, then choose Settings. This opens the full settings page, not the short dropdown.
3. In the left sidebar, under General, click View options.
4. Check Show week numbers. Google saves view settings automatically, so there is no confirm button.
5. Click the back arrow to return to your calendar.

Numbers appear beside each week row in the small calendar in the top left sidebar, and down the left edge of Month view. Google does not publish documentation for this checkbox, so treat the sidebar mini calendar as the reliable place to read the number. If you are in Day or Week view and see nothing, that is normal.

Google Calendar on Android and iPhone

The Google Calendar mobile apps have no week number setting. Google's own settings documentation for Android lists no such option, and there is no toggle to find. Two things work in practice: open Google Calendar in a mobile browser and request the desktop site, or check the number on a computer before you leave your desk. The week number is the same everywhere, so a glance at the desktop sidebar is usually enough.

Microsoft Outlook

Outlook is really four different apps, and the setting sits in a different place in each one. Microsoft's instructions cover Outlook for Microsoft 365, Outlook 2024, Outlook 2021, and New Outlook for Windows.

Turning the setting on in one client does not switch it on in the others, even when they open the same mailbox. If you use the desktop app at work and the web app on a laptop, you have to do it twice.

New Outlook for Windows

1. Open your calendar and select the View tab.
2. Choose Calendar settings.
3. Go to Calendar > View.
4. Under Calendar appearance, select Show week numbers, then choose Save.
5. Switch the calendar to Month on the ribbon. The numbers run down the left margin.

Microsoft documents this specifically for Month view, so do not expect numbers in Day, Week, or Work Week.

Classic Outlook for Windows

If your Outlook still has a File tab, you are on the classic version.

1. Select File > Options > Calendar.
2. Scroll to Display options.
3. Tick Show week numbers in the month view and in the Date Navigator, then click OK.

Classic Outlook is the only version that also puts the numbers in the Date Navigator, the little month calendar in the navigation pane. If that pane is collapsed you will not see them there, but Month view still shows them.

Outlook on the web and Outlook.com

Open the calendar, click the settings gear, then go to Calendar > View and turn on Show week numbers. Save if prompted, then switch to Month view. The web version also has a setting for which week counts as the first week of the year, which matters more than most people expect. More on that below.

Outlook for Mac

Microsoft's week numbers article does not list Outlook for Mac, so there is no documented path from Microsoft to point you at. In current builds the option is reported under Outlook > Settings (older versions say Preferences) > Calendar, in the calendar options group. If it is not there in your build, the practical fallback is to read week numbers in Outlook on the web with the same account. Do not try the Windows File > Options route on a Mac; that menu does not exist there.

Outlook mobile

Microsoft's documented procedures cover the desktop and web clients only. There is no equivalent switch in the Outlook apps for iOS and Android.

Apple Calendar

Apple splits this across two places: an app setting on Mac, and a system setting on iPhone and iPad.

Mac

1. Open Calendar.
2. From the menu bar, choose Calendar > Settings.
3. Click the Advanced tab.
4. Tick Show week numbers.

Apple's own description is unusually generous here: the setting shows week numbers in Week, Month, or Year view, which is wider coverage than either Google Calendar or Outlook offers.

iPhone and iPad

1. Open the Settings app.
2. Tap Apps, then Calendar. On older iOS versions, Calendar sits directly in the main Settings list.
3. Turn on Week Numbers.

Apple describes this as displaying the week number next to every week of the year. Open the Calendar app in Month view and the numbers sit alongside each week row. While you are on that screen, Start Week On controls which day your weeks begin, which affects how the grid lines up.

Apple documents Week Numbers for iPhone, iPad, and Mac. There is no matching option in the iCloud.com calendar, so if you plan in a browser you will need one of the other apps for the number.

When two calendars disagree about the week number

This is the real problem behind most searches for this topic, and it is not a bug. Different apps use different rules for deciding which week gets to be week 1.

Under ISO 8601, the international standard, weeks start on Monday and week 1 is the week containing the year's first Thursday. Three tests give the same answer: the week with the first Thursday, the week containing January 4, and the first week with at least four of its days in the new year. A consequence catches people out every January. If January 1 falls on a Friday, Saturday, or Sunday, it belongs to the last week of the previous year, not to week 1.

The common American convention is different: weeks start on Sunday, and the week containing January 1 is week 1 no matter how few days it has. That single difference is enough to put your calendar one number ahead of a colleague's for most of the year.

Getting them to match

Outlook gives you direct control on Windows. Go to File > Options > Calendar and look under Work time for First day of week and First week of year. The three choices for the first week are Starts on Jan 1, First 4-day week, and First full week. For ISO numbering, set Monday plus First 4-day week. Outlook on the web offers the same three options under a setting for which day the first week of the year starts on.

Google Calendar has a Start week on setting under the same View options page, but no control over the first-week-of-year rule. You take whatever numbering Google applies.

Apple Calendar takes its cue from the system rather than the app. On Mac, the Language & Region settings include a Calendar type and a First day of week option, and users who need ISO numbering report switching the calendar type to ISO 8601 there. Apple does not document how Calendar computes the number, so check the result rather than assuming.

The fastest way to verify any of this: look up the first full week of January in your calendar and compare it against a colleague's, or against a week number reference. If the two differ by one, the first-week rule is the culprit, not the app. For the current week number at a glance, use WeekLeft's live weeks left counter.

Troubleshooting

The setting is on but I see no numbers. Check which view you are in. Google shows them in Month view and the mini calendar, Outlook in Month view, and Apple Calendar in Week, Month, and Year view. Day view rarely shows anything.

It worked at the office but not at home. In Google Calendar the setting follows your account, so signing into the same account should carry it over; a hard refresh usually fixes a stale page. In Outlook, settings are per client, so the desktop app and the browser each need their own switch.

The option is missing entirely in Outlook. You may be on the other Outlook. New Outlook has no File tab and uses View > Calendar settings; classic Outlook uses File > Options. On a managed work account, an administrator policy can also hide or reset calendar options, in which case your IT team is the right stop.

My number is off by one. See the section above. Nothing is broken; two apps are applying two different definitions of week 1.

Frequently Asked Questions

Do I need an add-on or extension? No. Week numbers are a built-in display setting in Google Calendar on the web, Outlook, and Apple Calendar. Browser extensions exist for Google Calendar, mostly for custom numbering schemes such as a fiscal year that does not start in January.

Can I see week numbers on my phone? On iPhone and iPad, yes, through Settings > Apps > Calendar. Google Calendar and Outlook mobile apps have no such option.

Does turning this on change anything for other people? No. It is a display preference on your own calendar. Nobody else sees a difference, and your events are untouched.

Why do some years have 53 weeks? Under ISO 8601, a year has 53 weeks when the Gregorian year contains 53 Thursdays. Numbering restarts at 1 each January.

Which rule should my team use? Whichever one your customers and systems already use. If you work with European partners, manufacturing schedules, or logistics, ISO 8601 is the safe default. If week numbers only circulate inside a US team, consistency matters more than the standard itself.