First Day of Week Change in Windows 11: What It Does

Changing the first day of the week in Windows 11 only affects how dates are displayed in the calendar and in certain apps—it does not change any system settings, file timestamps, or scheduling logic. You can set it to any day (Sunday, Monday, etc.) in the Region settings, and it will immediately update the Calendar app, the taskbar clock popup, and any app that reads the system’s date format. Here’s everything that changes, what doesn’t, and how to avoid common confusion.

Background: Why Windows Has a First Day of Week Setting

The concept of a “first day of the week” is cultural and varies by country. In the United States, the week traditionally starts on Sunday; in much of Europe and many other regions, Monday is the first day. Windows has included this setting for decades, inherited from the older Control Panel Regional Options. It is part of the short date and long date format strings, which also control separators, leading zeros, and the order of day, month, and year.

When you change the first day, Windows does not alter any internal calendar calculations. It simply changes which column is leftmost in a month view and which day is considered the start when grouping by week in some apps. The setting is stored per user account, so changing it on one account does not affect other users on the same PC.

How the Setting Works in Windows 11

Windows 11 stores the first day of the week as part of the user’s regional format. You can find it in two places:

Settings > Time & Language > Language & Region – click “Regional format” and then “Change formats”.
Control Panel > Clock and Region > Region > Additional settings > Date tab – the same underlying setting.

When you change the value, Windows immediately refreshes the calendar. The taskbar clock popup (clicking the time) will show the new week layout. The Calendar app (Outlook, Windows Mail, and the built-in Calendar) will also reflect the change, provided they are set to use the system date format rather than their own override.

Importantly, the setting is stored as a locale-specific format. If you change your region to a country that uses a different first day, Windows will automatically update it. You can override it manually afterward.

What Actually Changes When You Switch the First Day

Here is a precise list of what is affected:

Calendar month view – the leftmost column becomes your chosen day, and the rows shift accordingly.
Week numbering in some apps – some calendar apps show week numbers (e.g., “Week 12”). The week number may change if the app uses the first day to determine which week a date belongs to. Windows’ own Calendar app does not show week numbers by default, but Microsoft Outlook does.
Taskbar clock popup – the mini calendar that appears when you click the clock.
Apps that read the system date format – many third-party apps, especially calendar widgets, will follow the system setting.

What does not change:

File timestamps – the last modified date of files is stored as an absolute timestamp and is not affected.
Task Scheduler – scheduled tasks that run “every Monday” still run on Monday regardless of the first day setting.
Excel and other spreadsheet date calculations – Excel has its own week system (WEEKDAY function) that you must configure separately.
System time zone – the time zone is independent.

How to Change the First Day of the Week in Windows 11

Follow these steps to change it:

Open Settings (Win + I).
Go to Time & Language > Language & Region.
Under “Regional format”, click Change formats.
Find the “First day of week” drop-down and select your preferred day.
Close Settings – the change applies instantly.

If you prefer the Control Panel route:

Open Control Panel > Clock and Region > Region.
Click “Additional settings” at the bottom-right.
Go to the Date tab.
Under “First day of week”, choose your day.
Click OK twice.

Note: If you change the region to a country that uses a different first day, Windows may override your custom setting. You can always change it back manually.

Common Problems and Misconceptions

One frequent issue: you changed the setting, but the Calendar app still shows Sunday first. This usually happens because the app has its own display preference. For example, Microsoft Outlook has a separate option: File > Options > Calendar > “First day of week”. That overrides the system setting. Similarly, Google Calendar in a browser has its own setting under Settings > “Week starts on”.

Another misconception is that changing the first day will change the “week number” in Windows Explorer or file properties. It does not. Week numbers are not shown in File Explorer at all.

A third issue: the setting sometimes resets after a Windows update. This can happen if the update changes your region or if you use a “sync your settings” account that pulls the regional format from another device. To prevent this, set the region to your own country and then manually set the first day.

Comparison: Windows 11 vs. Windows 10 vs. macOS

Windows 11 made the setting slightly more buried than Windows 10. In Windows 10, you could reach it via Settings > Time & Language > Date & time > “Change date and time formats”. In Windows 11, you must go through Language & Region. The underlying functionality is identical.

macOS has a similar setting in System Settings > General > Language & Region > Calendar > “First day of week”. It also affects the Calendar app but not file timestamps. Linux desktop environments vary; GNOME uses the system locale’s default, and you can change it with a command-line tool like gsettings.

One difference: Windows 11’s Calendar app (the one that opens when you click the clock) updates immediately. On macOS, the menu bar clock does not show a calendar popup by default, so the change is only visible in the Calendar app.

When You Might Want to Change It

You might want to change the first day if:

Your workplace or school uses a Monday-start week, and you want your personal calendar to match.
You are planning a trip to a country where the week starts on a different day, and you want to avoid confusion.
You are using a shared computer and prefer a different layout than the default for your region.

There is no performance or storage impact. It is purely cosmetic for display purposes.

Frequently Asked Questions

Does changing the first day of the week affect file dates?
No. File timestamps are stored as absolute date/time values (e.g., January 15, 2025, 14:30:00). Changing the first day only affects how dates are displayed in calendars and some apps, not the underlying data.

Why does my Outlook calendar still show Sunday first?
Outlook has its own setting that overrides Windows. Go to File > Options > Calendar > “First day of week” and set it to your preference. The same applies to Google Calendar in the browser.

Will changing the first day affect my scheduled tasks?
No. Task Scheduler uses the actual day of the week (Monday, Tuesday, etc.), not the “first day” setting. A task scheduled for “every Monday” will still run on Monday even if you set Sunday as the first day.

Does the setting sync across devices?
If you sign in with a Microsoft account and have “Sync your settings” enabled, the regional format may sync. However, the first day of week is part of the regional format, so it can sync. You can disable sync for regional settings in Settings > Accounts > Windows backup > Remember my preferences.

Why did the first day reset after a Windows update?
Windows updates can occasionally reset regional settings if they change your region or if the update modifies the user profile. Reapply the setting after the update. If it happens repeatedly, check that your region is set correctly and that you are not using a roaming profile.

Can I set the first day to any day, like Wednesday?
Yes, the drop-down includes all seven days. There is no restriction to Sunday or Monday.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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