How to Change an iPhone Alarm: Time, Sound, and More

You can adjust an alarm without changing your iPhone’s clock or other alarms. You’ll need an iPhone with the Clock app; menu labels can differ slightly by iOS version.

What You’ll Need

Your iPhone, switched on and with enough battery to remain powered at the alarm time.
The Clock app. It is usually on the Home Screen or in the App Library; search for “Clock” if you cannot find it.

Step-by-Step

Open Clock. Tap the Clock app, then tap Alarms at the bottom of the screen. If you use a different iOS version, the layout may differ slightly, but look for the alarm list.
Choose an existing alarm or add one. To change one already listed, tap its time or tap Edit and select the alarm. To make a separate alarm, tap the + button. Editing preserves that alarm; adding creates another one.
Set the time. On the edit screen, adjust the hour and minute using the time picker. Check AM or PM if your iPhone uses a 12-hour clock. In a 24-hour format, confirm the hour is correct. Tap Save or the confirmation control shown on screen.
Change when it repeats or what it is called. Tap Repeat to choose the days the alarm should sound, or leave the days unselected for a one-time alarm. Tap Label to give it a name, such as “Work.” Save the changes when prompted.
Choose an alarm sound and snooze setting. Tap Sound and select an available tone, or choose a song if that option is offered and configured on your iPhone. Check whether Snooze is on or off. Tap back or save as needed; the exact controls may vary slightly by version.
Save and verify it is on. Tap Save if it appears. Return to the alarm list and check the displayed time, repeat days, and enabled switch. A switch that is on indicates the alarm is active; an alarm shown in the list is not necessarily enabled.

Common Mistakes

Changing the wrong alarm: If several alarms have similar times or labels, read the time and repeat days before editing. Check the list again after saving.
Forgetting to enable it: Saving an alarm and turning it on are separate things. Confirm its switch is enabled, especially after making a new alarm.
Choosing the wrong AM or PM: A time that looks correct can be twelve hours off. Check the AM/PM indicator, or verify the hour in 24-hour format.
Setting a repeat schedule by mistake: Selecting weekdays means the alarm repeats on those days; leaving all days unselected generally makes it a one-time alarm. Review the schedule before leaving the editor.
Assuming silent mode disables alarms: The Ring/Silent switch and Focus settings do not normally turn off Clock alarms. However, the alarm’s sound selection and volume still matter.
Confusing an alarm with a sleep schedule: Sleep and wake-up schedules can have separate controls from regular alarms. If the alarm you want is part of a sleep schedule, look for its schedule settings rather than editing an unrelated alarm.

Tips

Use a clear label so you can identify alarms at a glance, especially if you keep several for different days.
For a one-time change, edit the alarm and then confirm its repeat days. For a different schedule, create a separate alarm if that makes it easier to keep the original intact.
Check the selected sound in the editor instead of relying only on its name. If the available sound choices differ on your device, select a tone shown in the list.
Alarm volume is controlled separately from the alarm’s selected sound. If it is too quiet, check Settings > Sounds & Haptics for the ringer and alerts volume; this path may differ slightly by iOS version. Changing it can also affect other alerts.
If you need an alarm at a particular local time while travelling, check the iPhone’s time and time-zone settings as well as the alarm. Avoid assuming an alarm’s displayed time will compensate for a manually incorrect clock.

Troubleshooting

The alarm did not sound: Open Clock and verify the alarm is enabled, set to the expected time, and set to repeat on the relevant day if needed. Check the selected sound and ringer and alerts volume. Make sure the iPhone was powered on and had battery; an iPhone that shuts down cannot sound an alarm.
The alarm sounds at the wrong time: Check AM/PM, repeat days, and the iPhone’s date, time, and time-zone settings. The path is generally Settings > General > Date & Time, though it may differ slightly by version. If automatic time settings are available, check whether they are enabled.
The sound is silent or unexpectedly quiet: Reopen the alarm’s Sound setting and select a tone rather than assuming the current choice will be audible. Raise the ringer and alerts volume, then make a short test alarm a few minutes ahead and cancel it afterward.
You cannot find the alarm or editing controls: Search for Clock from the Home Screen or App Library. In the Alarms tab, tap the listed alarm or use Edit; button placement and wording can vary slightly by iOS version.
Your changes do not seem to stick: Return to the alarm list and check the time and on/off switch. Reopen the alarm, make the change, and use Save or the on-screen confirmation control before leaving. If the app is unresponsive, close and reopen Clock, then check again.
A sleep alarm behaves differently: Look for the sleep or wake-up schedule in the Clock app or Health app. Those controls may be separate from standard alarms, and their location can differ by iOS version.

Frequently Asked Questions

How do I change the sound of an iPhone alarm?

In Clock, open Alarms, select the alarm, tap Sound, and choose an available tone. Save or return to the alarm list as prompted, then check that the alarm remains enabled.

How do I change an alarm from AM to PM?

Edit the alarm and use the time picker to choose the correct hour and AM or PM. If your phone displays 24-hour time, choose the matching hour in that format instead.

Can I make an iPhone alarm go off only once?

Yes. Edit the alarm and open Repeat. Leave the days unselected for a one-time alarm, then save and check that the alarm is enabled.

Will my iPhone alarm sound when the phone is on silent or Do Not Disturb?

Clock alarms generally still sound when the Ring/Silent switch is set to silent or a Focus mode is active. The selected alarm sound and ringer and alerts volume can still affect how audible it is.

Does an iPhone alarm work when the phone is turned off?

No. Keep the iPhone powered on and charged enough to remain on through the alarm time. If the battery runs out or the phone shuts down, the alarm cannot sound.

How do I delete an iPhone alarm instead of changing it?

In Clock, open Alarms, tap Edit, then use the delete control beside the alarm, or swipe left on it if that option is available. Confirm deletion if asked; controls may differ slightly by iOS version.

Sources: Apple Support. Menus and buttons can differ slightly by version. Spotted something out of date? Tell us.