How to Change the Date and Time on Your Computer

Where to find the date and time settings

Your computer stores the current date and time in a system setting that affects everything from file timestamps to calendar apps. On Windows, you reach this setting through the system clock in the bottom right corner of your screen. On Mac, the date and time controls live in System Settings under General, then Date & Time.

Both operating systems let you set the date and time manually, or you can let your computer sync automatically with an internet time server. Most people leave automatic sync on, which means your computer updates itself whenever it connects to the internet. If your date keeps drifting wrong, automatic sync is usually the faster fix than manual adjustment.

Key Takeaways

On Windows, right-click the clock in the bottom right corner and select "Adjust date and time" to open the settings panel.
On Mac, go to System Settings, click General, then Date & Time, and toggle "Set date and time automatically" on or off.
Turning on automatic time sync fixes most date problems without manual work, since your computer syncs with internet time servers.
If you set the date manually, you must also set the time, or your computer will show the wrong moment for file timestamps and scheduled tasks.
After you change the date or time, restart any open programs that depend on the current time, like calendar or email apps.

Changing the date and time on Windows

Right-click the clock display in the bottom right corner of your taskbar. A small menu appears with the option "Adjust date and time." Click it to open the Settings window. You will see a toggle labeled "Set time automatically" near the top. If this toggle is already on (blue), your computer is syncing with an internet time server and you should not need to change anything manually.

If you need to set the date or time yourself, turn off the "Set time automatically" toggle first. Two new buttons will appear: "Change" under the date section and another "Change" under the time section. Click the date "Change" button to open a calendar picker. Select the correct month and year using the arrows, then click the correct day. Click "Change" under the time section next, and use the hour, minute, and second fields to enter the correct time. Click "OK" when you finish, and the new date and time take effect when ready.

Changing the date and time on Mac

Click the Apple menu in the top left corner and select "System Settings." In the sidebar, click "General," then scroll down and click "Date & Time." You will see a toggle labeled "Set date and time automatically." If this toggle is on, your Mac is syncing with an internet time server and you do not need to make changes.

To set the date and time manually, turn off the "Set date and time automatically" toggle. New fields appear where you can enter the date and time. Click in the date field and type the date in the format your Mac expects (usually MM/DD/YYYY). Click in the time field and type the time in hours, minutes, and seconds. Your Mac updates the system clock as soon as you finish typing. Close the System Settings window when you are done.

When automatic sync is the better choice

Automatic time sync is turned on by default on both Windows and Mac because it solves most date and time problems without any work from you. Your computer connects to a time server on the internet (usually run by your internet provider or a public service) and downloads the correct time. This happens in the background whenever your computer is online, so you never have to think about it.

The only reason to turn off automatic sync is if your computer is not connected to the internet, or if you need to set a custom date and time for testing or troubleshooting purposes. If your date keeps showing wrong even with automatic sync on, the problem is usually that your computer is not connecting to the internet properly, not that the sync feature is broken. Check your internet connection first before you switch to manual time entry.

What happens after you change the date or time

Once you change the date or time, the change takes effect when ready on your computer. Any new files you create will have timestamps using the new date and time. Programs that depend on the current time—like calendar apps, email clients, and scheduling software—may not update their display right away. Close and reopen these programs to make sure they show the correct information based on your new system time.

If you changed the time by more than a few minutes, some programs may behave unexpectedly. For example, a calendar app might not show events that are scheduled for times that have already passed according to the old clock. This is why automatic sync is safer: it makes small adjustments gradually rather than jumping the time forward or backward all at once.

Common mistakes when setting the date manually

The most common mistake is changing only the date and forgetting to change the time, or vice versa. Your computer needs both pieces of information to create accurate timestamps. If you set the date to today but leave the time at 3:00 AM when it is actually 2:00 PM, files created in the afternoon will show a morning timestamp. Always check both fields before you click OK or confirm the change.

Another mistake is using the wrong date format. On Windows, the format is usually MM/DD/YYYY (month first), but some regions use DD/MM/YYYY (day first). If your computer is set to a region that uses day-first format and you type 12/03/2024 thinking it means December 3rd, your computer will interpret it as March 12th instead. Check your region settings if the date keeps appearing wrong after you enter it.

Fixing a date that keeps resetting

If you set the date and time manually, but they reset to the wrong time the next time you restart your computer, automatic sync is probably turning back on. Check your date and time settings again and make sure the automatic sync toggle is in the position you want it. If you want manual control, it should be off. If you want automatic sync, it should be on.

If the date keeps resetting even when automatic sync is off, your computer's internal clock battery may be failing. This is a hardware issue that requires a technician to fix. For now, you can work around it by turning automatic sync back on so your computer corrects the time whenever it connects to the internet. This is not a permanent solution, but it will keep your file timestamps accurate until you can have the battery replaced.

Frequently Asked Questions

Will changing the date and time affect my files or programs?

Changing the date and time will not damage your files or programs. However, any new files you create after the change will have timestamps based on the new date and time. Programs that depend on the current time, like calendar or email apps, may show incorrect information until you close and reopen them. Restart these programs after you change the system time.

What is the difference between manual and automatic time sync?

Automatic sync connects your computer to an internet time server and updates the date and time in the background without any action from you. Manual time entry means you type in the date and time yourself. Automatic sync is more accurate and requires no work, so it is the better choice for most people. Use manual entry only if your computer is offline or you need a custom date for testing.

Can I set a different time zone without changing the date and time?

Yes. On Windows, open Date & Time settings and look for the "Time zone" dropdown separate from the date and time fields. On Mac, the time zone option is in the same Date & Time panel. Changing your time zone will adjust what time your computer displays, but it does not change the underlying system time. Your computer will show the correct local time for your new location.

Why does my computer show the wrong date after I restart it?

If the date resets after a restart, automatic sync is probably turning back on and correcting the time based on an internet server. Check your date and time settings to see if automatic sync is enabled. If you want to keep a manual date, make sure the automatic sync toggle is off. If automatic sync keeps turning itself back on, your computer may have a failing clock battery that needs replacement.

Does changing the date affect my password or login?

Changing the date and time will not affect your password or your ability to log in. Your login credentials are stored separately from the system clock. However, some security features like two-factor authentication may depend on the correct time, so keeping your date and time accurate is still a good idea for security reasons.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.