A missed alarm is more than annoying. These eight checks fix almost every case, in roughly the order they cause problems.
- Alarm volume. Open Settings → Sound and vibration and raise the Alarm slider. It is separate from media and ringtone volume.
- Do Not Disturb. In Settings → Sound → Do Not Disturb make sure Alarms is allowed to interrupt.
- Battery optimisation. In Settings → Apps → your alarm app → Battery, choose Unrestricted (wording differs by phone). Aggressive battery managers on some phones stop background apps.
- Alarms and reminders permission. On Android 12 and later, apps need the Alarms & reminders permission to set exact alarms. Check it under Settings → Apps → Special app access.
- Notifications. Allow notifications for the alarm app. Some apps use a notification to show and silence the alarm.
- Do not swipe the app away. On a few phones, force-stopping an app cancels its alarms. Leave it alone.
- Time zone and clock. If the phone is set to Automatic date and time, alarms follow travel. If it is manual, a wrong zone shifts them.
- Restart and update. After a system update, restart the phone and open the alarm app once so it can register its alarms again.
Test before you rely on it
Set a test alarm two minutes ahead, lock the screen and wait. Repeat with the phone on battery saver. If it rings both times, you are set.
Also read: alarm volume and Do Not Disturb explained and tips for waking up more easily.