The quickest way to change your computer's time

On Windows, click the time in the bottom-right corner of your screen and select "Change date and time settings." On Mac, go to System Settings (or System Preferences on older versions), click "General," then "Date & Time," and toggle off "Set date and time automatically" if it's on. After that, you can type in the correct time and date directly.

The reason your computer might show the wrong time is usually that it lost power, your battery died, or the automatic time sync turned off. Once you change it manually, the system will remember the new setting until something interrupts it again.

Key Takeaways

  • Windows users click the system clock in the bottom-right corner and select "Change date and time settings" to adjust the time manually.
  • Mac users open System Settings, navigate to "Date & Time," and turn off automatic time sync before entering a new time.
  • If you want your computer to update the time automatically, turn on the "Set date and time automatically" option in the same menu.
  • Your computer's internal battery (called a CMOS battery on Windows machines) keeps the time running even when powered off; if it fails, the time resets repeatedly.

Changing the time on Windows 10 and Windows 11

Right-click the time display in the bottom-right corner of your taskbar and select "Adjust date and time." This opens the Date & Time settings panel. You'll see a toggle for "Set time automatically"—if it's already on, your computer should sync with an internet time server, so you may not need to change anything manually.

If you need to set the time yourself, turn off "Set time automatically," then click "Change" under the manual time entry section. A small window will pop up where you can type the correct date and time. Enter the month, day, year, and time in the format shown, then click "Change." Windows will explore the new time when ready.

After you've set the correct time, you can turn "Set time automatically" back on if you want Windows to keep itself synced. This is the easiest option for most people because your computer will adjust for daylight saving time and stay accurate without any work from you.

Changing the time on Mac

Click the Apple menu in the top-left corner and select "System Settings" (on newer Macs) or "System Preferences" (on older ones). Look for "General" in the sidebar, then click "Date & Time." You'll see a checkbox that says "Set date and time automatically"—uncheck it if you want to enter a time manually.

Once you've unchecked that box, the date and time fields become editable. Click on the date field and type the correct date, then click on the time field and enter the correct time. Mac will save your changes as soon as you finish typing. If you want automatic syncing again, just check the "Set date and time automatically" box.

Why your computer's time keeps resetting

If you change the time but it resets to the wrong time the next time you restart your computer, the problem is usually your CMOS battery (on Windows) or the internal clock battery (on Mac). This small battery keeps your computer's clock running even when the machine is powered off. When it dies, the time reverts to a default or stops updating.

You can test this by setting the time, shutting down your computer completely for a few hours, and then turning it back on. If the time is wrong again, the battery likely needs replacement. On laptops, this usually requires opening the case or taking it to a technician. On desktop computers, it's a small coin-shaped battery on the motherboard that you can often replace yourself, though you should consult your computer's manual first.

Another reason the time might reset is if your internet connection drops and "Set time automatically" is on. Your computer can't sync with the time server without internet, so it falls back to whatever time it had stored. Once your connection returns, it should sync again automatically.

Using automatic time sync instead of manual changes

Turning on automatic time sync is almost always easier than changing the time manually. Both Windows and Mac will connect to an internet time server (usually run by the National Institute of Standards and Technology) and update your clock to match. This happens in the background without any action from you.

Automatic sync also handles daylight saving time changes automatically. If you set the time manually, you'll need to remember to adjust it twice a year when daylight saving begins and ends. With automatic sync on, your computer does this for you.

The only reason to turn off automatic sync is if you want to run your computer on a different time zone than your location, or if you're testing software that depends on a specific time. For everyday use, leaving it on is the best choice.

Changing your time zone without changing the time

If your clock shows the right time but in the wrong time zone, you need to change the time zone setting, not the time itself. On Windows, open Date & Time settings and scroll down to "Time zone." Click the dropdown and select your correct time zone from the list. Windows will automatically adjust the displayed time to match.

On Mac, open Date & Time settings and look for the "Time zone" section. Click the dropdown and search for your city or time zone. Mac will update the displayed time to match your new zone. If you have "Set date and time automatically" turned on, your computer will also sync to the correct time for that zone.

What to do if the time won't change

If you've tried to change the time but it won't stick, check whether "Set time automatically" is turned on. If it is, your computer will override any manual change you make and sync back to the internet time server. Turn off automatic sync first, make your change, and then decide whether to turn it back on.

On Windows, make sure you're logged in as an administrator. Changing the system time requires admin rights, so if you're using a standard user account, you won't be able to modify it. Ask whoever set up your computer to change the time for you, or switch to an admin account.

If you're on a work or school computer, your network administrator may have locked the time settings so employees or students can't change them. In that case, you'll need to contact your IT department to request a time change. This is common on managed networks to keep all computers synchronized.

Frequently Asked Questions

Why does my computer show the wrong time when I first turn it on?

Your computer's internal battery (CMOS battery on Windows, clock battery on Mac) keeps time when the machine is off. If this battery is dying or dead, the clock resets to a default time or stops updating. You can test this by setting the time, shutting down for several hours, and checking if it's wrong again. If it is, the battery likely needs replacement.

Can I change my computer's time zone without changing the actual time?

Yes. In Date & Time settings on both Windows and Mac, there's a separate "Time zone" dropdown. Change that instead of the time itself, and your computer will adjust the displayed time automatically to match the new zone. This is useful if you've moved or travel frequently.

What happens if I set my computer's time to the future or past?

Some programs and websites may behave strangely if your computer's time is far off. Email, file timestamps, and security certificates can all act up. It's best to keep your time accurate. If you need to test software with a different time, use automatic sync to restore the correct time when you're done.

Does changing the time affect my files or programs?

Changing the time won't delete or damage your files. However, it can affect file timestamps (the dates shown in your file explorer) and may confuse programs that depend on accurate time, like email clients or backup software. Once you set the time back to normal, these programs should work correctly again.

Why should I use automatic time sync instead of setting the time manually?

Automatic sync keeps your computer accurate without any work from you, handles daylight saving time changes automatically, and prevents the time from drifting. Manual time setting requires you to remember to adjust it twice a year and can slowly become inaccurate over time.