To set a 12-hour clock in Windows 10, open Control Panel, select Change date, time, or number formats, and on the Formats tab choose Short time and Long time formats that start with a lowercase h and end with tt. Select Apply, then OK, and Windows shows times with AM and PM.
Applies to: Windows 10.
Before you start
Windows does not have a single 12-hour or 24-hour switch. The clock style comes from your regional formats, which are the rules Windows uses to write dates, times, numbers, and currency. Changing the time format only changes how the time is written. It does not move the clock forward or back, and it does not change your time zone.
Two terms appear in the steps:
- Short time is the compact version of the time, with hours and minutes.
- Long time is the fuller version that also includes seconds.
The steps change both, so the two versions match everywhere Windows shows a time.
Set the 12-hour clock in Control Panel
This route takes about a minute.
- In the search box on the taskbar, type control panel, and then select Control Panel. The Control Panel window opens.
- Select Change date, time, or number formats. It is a small link under the clock and region category. The Region dialog box opens.
- Stay on the Formats tab and find the Date and time formats section.
- Open the Short time list and select a format that starts with a lowercase h and ends with tt. Lowercase h means a 12-hour clock, and tt adds AM or PM.
- Open the Long time list and select the matching 12-hour format, the one with a lowercase h, seconds (ss), and tt.
- Select Apply, and then select OK. The dialog box closes and your new format is saved.
The same steps appear in Microsoft’s article on how to switch between a 12-hour clock and a 24-hour clock.
What the time format letters mean
The lists on the Formats tab show letter codes instead of sample times. This table explains the ones that matter for a 12-hour clock. The meanings come from Microsoft’s Windows documentation for time format pictures.
| Code | What it means | 3:05 in the afternoon looks like |
|---|---|---|
| h | 12-hour clock, no leading zero | 3 |
| hh | 12-hour clock, with a leading zero | 03 |
| H | 24-hour clock, no leading zero | 15 |
| HH | 24-hour clock, with a leading zero | 15 |
| mm | Minutes, with a leading zero | 05 |
| ss | Seconds, with a leading zero | 00 |
| tt | The AM or PM marker | PM |
The quick rule: a lowercase h gives you a 12-hour clock and an uppercase H gives you a 24-hour clock. Always pick a 12-hour format that includes tt. Without it, 3:05 in the morning and 3:05 in the afternoon look the same.
Open the Region dialog box with the Run command
If you cannot find the link in Control Panel, a shortcut opens the classic Region dialog box directly.
- Press the Windows key + R. The Run box opens.
- Type intl.cpl and press Enter. The Region dialog box opens.
- Change Short time and Long time as described above, then select Apply and OK.
Use the Settings app instead
Windows 10 also has regional format options in the Settings app.
- Select Start > Settings > Time & Language.
- Select Region.
- Select the link for changing data formats, near the regional format section.
- Choose a short time and a long time that show AM or PM.
The wording of that page has changed between Windows 10 versions, so your screen may not match another guide exactly. If you do not see these options, use the Control Panel steps. They lead to the same formats.
Confirm the change or go back to 24-hour time
Look at the clock at the right end of the taskbar. A 12-hour clock shows AM or PM after the time, and afternoon hours no longer appear as 13 through 23. Once the 12-hour format is on, the AM and PM choice also appears when you create an alarm in Windows 10, so double-check it before saving.
To go back, repeat the steps and select the formats that start with an uppercase H. The 24-hour choices are HH:mm for Short time and HH:mm:ss for Long time.
Troubleshooting
- The lists have no format with tt: the choices depend on the regional format selected at the top of the Formats tab. Select a format for a region that uses AM and PM, such as English (United States), and then open the time lists again. This also changes how Windows writes dates, numbers, and currency, so check those afterward.
- You need a format that is not in the lists: on the Formats tab, select Additional settings, and then open the tab that holds the time settings to make your changes.
- An app still shows 24-hour time: close the app and open it again. An Access database, for example, may need to be closed and reopened before new regional settings take effect. Some apps and websites also have their own time format option that ignores Windows.
- The format is right but the time is wrong: that is a clock or time zone problem, not a format problem, so change the date and time in Windows 10 instead. If the hour is off for Manila, the fix is the time zone, explained in setting Philippine time in Windows 10.
- The options are greyed out or change back: on a work or school PC, your organization may manage regional settings. Ask your IT administrator to make the change.
Frequently asked questions
Does a 12-hour clock change the actual time on my PC?
No. It only changes how the time is written. 15:30 and 3:30 PM are the same moment, and your time zone stays as it was.
Should I change both Short time and Long time?
Yes. If you change only one, some places in Windows show AM and PM while others still use 24-hour time.
Will Outlook follow the new format?
Yes. Outlook uses the country or region settings for your computer to decide how times appear, so the calendar follows the Windows format.
Can I change the date format in the same place?
Yes. The date lists sit on the same Formats tab, and changing the date format in Windows 10 explains them.
Are the steps the same in Windows 11?
The Control Panel steps are nearly the same. In Windows 11, the steps start at Control Panel > Clock and Region > Change date, time or number formats. In the Settings app, regional formats are under Time & language > Language & region.
Is Windows 10 still supported?
Microsoft ended support for Windows 10 on October 14, 2025. These settings still work on existing Windows 10 PCs.
Related: hide the clock on the taskbar in Windows 10.
Matt Jacobs writes and maintains the guides on Support Your Tech, which he started in 2017. He spent most of his career keeping small-business PCs running and still takes the occasional consulting job, so the steps here come from fixing the same problems on other people’s computers. Every guide is checked on his own Windows 11, Windows 10, Mac, iPhone and iPad before it goes up.