The fastest way to change your computer's time

On Windows, right-click the time in the bottom-right corner of your screen and select Adjust date and time. Toggle Set time automatically off, then click Change under "Set the date and time manually" and enter the correct time. On Mac, open System Settings, go to General > Date & Time, uncheck Set date and time automatically, and type in the new time.

Both methods take under a minute. If your computer's clock keeps drifting or resetting, the issue is usually your system battery, not the software — that requires hardware repair, not a settings change.

Key Takeaways

  • Windows users right-click the system clock, turn off automatic time setting, and manually enter the correct time in the date and time menu.
  • Mac users open System Settings, navigate to Date & Time, disable automatic synchronization, and type the new time directly.
  • Turning off automatic time setting is necessary before you can enter a custom time on either operating system.
  • If your clock resets after you change it, your computer's internal battery may be failing and will need replacement by a technician.

Windows: Step-by-step instructions

Locate the time display in the bottom-right corner of your taskbar. Right-click directly on the time or date. A menu will appear with several options — select Adjust date and time. This opens the date and time settings panel.

Look for the toggle labeled Set time automatically and switch it to the off position. Once automatic synchronization is disabled, a new option appears: Change under "Set the date and time manually." Click that button. A smaller dialog box opens where you can type the hour, minute, and second. Enter the correct time and click Save. Your system clock updates when ready.

If you also need to change the date, the same Change button handles both — the dialog includes fields for month, day, and year alongside the time fields.

Mac: Step-by-step instructions

Click the Apple menu in the top-left corner and select System Settings (or System Preferences on older macOS versions). In the sidebar, find and click General, then select the Date & Time tab.

You will see a checkbox labeled Set date and time automatically. Uncheck this box to unlock manual time entry. Once unchecked, the time field becomes editable. Click in the time field and type the correct time in the format your system displays (usually HH:MM AM/PM or 24-hour format). Press Enter to confirm. The change takes effect when ready.

The date field works the same way — uncheck the automatic setting and you can edit the date directly if needed.

Why your computer's time might be wrong

Most computers synchronize their clocks with internet time servers automatically. If your time is off by a few minutes or hours, automatic synchronization was either disabled or your computer lost internet connection while the setting was off. Turning automatic synchronization back on solves this in seconds.

If your clock is consistently wrong by the same amount every time you restart, or if it resets to an old date after you change it, your computer's CMOS battery — a small internal battery that keeps the system clock running when the computer is powered off — is likely failing. This is a hardware issue that requires opening the computer case or taking it to a technician. No software setting will fix it permanently.

Turning automatic time synchronization back on

On Windows, follow the same steps as before: right-click the system clock, select Adjust date and time, and toggle Set time automatically back to the on position. Your computer will sync with internet time servers within a few seconds.

On Mac, open System Settings > General > Date & Time and check the box next to Set date and time automatically. Your Mac will synchronize when ready. This is the default setting, so if you have not changed it manually, your time should already be correct unless your internet connection is down.

What to do if the time keeps changing back

If you set the time manually and it reverts to the wrong time after restart or after a few hours, your computer is likely re-synchronizing with an internet time server. Check whether automatic time setting is actually turned on — you may have thought you disabled it but the toggle did not save. Repeat the steps above and watch the toggle switch to confirm it moves.

If automatic synchronization is definitely off and the time still changes, your computer may be connecting to a network time server through a domain or workplace network setting that overrides your manual choice. This is common on work computers. Contact your IT department or network administrator — they control the time setting on managed devices.

Changing time zone instead of the time itself

If your clock shows the correct time but in the wrong time zone, you are changing the wrong setting. On Windows, right-click the system clock, select Adjust date and time, scroll down to Time zone, and select your correct zone from the dropdown. On Mac, open System Settings > General > Date & Time and click Time Zone to choose your location.

Changing the time zone automatically adjusts the displayed time to match your location. You should not need to manually set the time if you only need to fix the zone.

Frequently Asked Questions

Why does my computer's time reset every time I restart it?

Your CMOS battery is likely dead or dying. This small internal battery keeps the system clock running when your computer is off. When it fails, the clock resets to a default date every restart. You will need to replace the battery, which usually costs $10 to $30 in parts but requires opening the computer case. A technician can do this, or you can do it yourself if you are comfortable with hardware.

Can I set my computer to a different time zone without changing the actual time?

No. Changing the time zone automatically adjusts the displayed time to match that zone. If you need your clock to show a time that does not match your actual location, you would have to manually set the time after changing the zone, but this is not recommended — it will confuse scheduling and time-stamped files.

What if I do not see the "Set time automatically" option?

On Windows, make sure you are in the full Date & Time settings panel, not just the quick clock popup. On Mac, check that you are in System Settings and not an older System Preferences window. If the option is grayed out, your computer may be managed by a network administrator who has locked the setting.

Does changing the time affect my files or programs?

Changing the system time can cause issues with file timestamps, scheduled tasks, and programs that rely on accurate time (like security certificates or backup software). Change your time only when necessary, and turn automatic synchronization back on as soon as you are done.

My computer is on a network — can I still change the time manually?

On personal networks, yes. On workplace or school networks, probably not — a network administrator usually controls time settings on managed devices to keep all computers synchronized. If you need to change the time on a work computer, contact your IT department.