When an Android alarm does not go off, the alarm itself is rarely broken. It is usually a setting sitting next to it: Do Not Disturb with alarms blocked, silent mode with vibration off, the alarm volume turned down, or Battery Saver. The alarm still shows as switched on: you wake at 8:40 and the 7:30 one never made a sound.
Below are eight causes from Google’s official help for the Clock app and from Samsung’s help pages, the common ones first. If you use a different alarm app, there is a section on that at the end. If you would rather not read it all, the alarm check keeps only the causes that fit your clock app and your problem.
1. Will the alarm go off in Do Not Disturb?
Yes, the alarm goes off in Do Not Disturb as long as alarms are allowed in the mode’s exceptions. On many phones that is the default: Motorola’s help, for one, says alarms and media sounds are allowed by default but can be turned off. Turn them off and Do Not Disturb silences the alarm along with everything else.
On Android the check is Settings → Modes → your mode → Notification filters → “Alarms & other interruptions”. Older versions had a “Total silence” option, and Google’s help says of it plainly: your alarms won’t make noise.
If DND did silence the alarm, Clock tells you afterwards: “Do Not Disturb silenced your alarm.” On Samsung the same place is the sounds section inside Do Not Disturb settings, with a separate slider for alarms.
2. Will the alarm go off if the ringer is off?
Google’s help does not answer this directly for the phone’s silent mode. Clock’s help has one line: “If your ringtone is set to silent and vibration is off, your alarm won’t go off.” It sits in the section about the alarm’s sound, so it is about the alarm’s own ringtone.
So check the alarm itself. If its sound is set to silent and vibration is off, it goes off without a sound. Clock warns you about this and tells you to choose a different sound.
Samsung has a separate setting that silences the alarm together with system sounds; it is covered in the Samsung section below.
3. Alarm volume is separate from the ringer
A quiet or inaudible alarm usually means its own volume slider is down: the alarm has one, separate from calls and media. And here is the trap: according to Android’s help, when you are not listening to anything, the volume buttons change media volume. You can press “up” all evening and never touch the alarm.
Google’s Clock also warns you if the alarm went off with the volume below 30%, which is easy to sleep through. Both the volume and how long an alarm rings are set in Clock’s settings: the “Alarm volume” slider and “Silence after”.
4. Two alarms too close together
If two alarms are less than five minutes apart, the first one may be cancelled. That rule comes from Google’s help, and the advice there is simple: leave a five-minute window between them.
5. Music instead of a ringtone
If your alarm plays a track from YouTube Music or Spotify, you need a paid subscription, as Google’s help notes. Free Spotify only lets you pick a playlist and may play ads. A plain system ringtone is the safer choice.
6. Battery Saver and Clock notifications turned off
Battery Saver may have prevented your alarm from going off: Clock’s help says so in those words. The fix from the same page: turn Battery Saver off, or add Clock as an essential app in Battery Saver settings.
The same page covers one more case. With notifications for the Clock app switched off, it shows: “To hear your alarms, turn on Clock notifications in Settings.” You turn them back on in the phone’s settings, under the Clock app’s notifications.
7. Samsung alarm not going off
Samsung has three causes of its own, all described in its help pages.
The first is “Silence alarms when system sound is off” in the Clock app, under More options → Settings. With it on, the alarm goes quiet along with system sounds and only vibrates. Samsung suggests turning it off if your alarm only vibrates.
The second is headphones. Sound Assistant has an option to play alerts through headphones, so the alarm can go to Bluetooth earbuds sitting in their case. Samsung’s official troubleshooting says to switch the alarm off there if you cannot hear it.
The third: with Samsung’s strong protection enabled, alarms do not work after a restart until the password is entered. If the phone updated and restarted overnight, in the morning it is waiting to be unlocked. Samsung’s suggestion is to turn off automatic restart or the secure startup feature.
8. The phone was switched off
An alarm will not go off on a phone that is powered down. Samsung says it directly: Clock and its alarm do not work while the device is off. The safer habit is to silence the phone at night rather than switch it off.
If the alarm is in another app
A third-party alarm fires even when the phone is in deep sleep, provided the app sets it as a proper alarm clock (the setAlarmClock method): per the Android documentation, the system exits Doze shortly before such alarms fire. Ordinary exact reminders are deferred in that mode.
Two things break any such alarm:
- A restart. All scheduled alarms are cancelled on shutdown, and the app has to set them again after the phone boots. That only works if the app has been opened at least once.
- The Force stop button in the app’s settings. Since Android 15, force-stopping an app cancels everything it had scheduled until you open it again.
If reminders arrive late rather than not at all, that is a different story, about exact alarms. It has its own article, and the checking order for your phone brand is in the notification settings checker.
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