How to Fix a Phone Alarm That Does Not Go Off

Published 2026-10-16 · Marion Phone Repair

You set an alarm on your phone, confirmed the time, saw the alarm icon in the status bar, went to sleep — and woke up late because the alarm never sounded. Missed alarms are one of the most frustrating phone issues because the consequences are immediate and the cause is not obvious. The alarm app on both iPhone and Android is generally reliable, but several settings, features, and edge cases can prevent it from firing.

Fix 1: Check the volume

The alarm volume is controlled separately from the ringer volume and media volume on most phones, but the separation is not always obvious:

iPhone

• Alarms use the Ringer and Alerts volume, not the media volume. Go to Settings, Sounds and Haptics (or Sounds), and check the Ringer and Alerts slider. If this slider is all the way down, alarms will be silent even if media volume is at maximum
• The physical volume buttons on the side of the iPhone adjust either the ringer volume or the media volume depending on context. If Change with Buttons is enabled under Sounds and Haptics, pressing the volume buttons when no media is playing adjusts the ringer (and alarm) volume. If you accidentally turned it down, alarms will be quiet or silent
• The silent switch (the physical switch on the left side of the iPhone) does NOT silence alarms. If your alarm is not sounding and the silent switch is engaged, the switch is not the cause — check volume settings

Android

• Press a volume button to bring up the volume slider, then tap the three-dot menu or the settings icon to expand all volume channels. You should see separate sliders for Media, Call, Ring, and Alarm. Make sure the Alarm slider is turned up
• On Samsung phones, go to Settings, Sounds and vibration, Volume, and check the Alarm slider specifically
• Some Android phones link the alarm volume to the ringer volume by default. If your phone is on vibrate or silent, this can mute the alarm. Check Settings, Sound, and look for a setting that links or separates alarm volume from other volumes

Fix 2: Check Do Not Disturb settings

Do Not Disturb (DND) is the most common cause of missed alarms because it is designed to silence everything — and on some configurations, it silences alarms too:

iPhone

• By default, iPhone alarms DO sound during Do Not Disturb and all Focus modes. However, if you created a custom Focus mode and modified its settings, alarms may be affected
• Check each Focus mode you use: Settings, Focus, select the mode, and verify that alarms are not being silenced. The built-in Sleep Focus specifically should allow alarms — check Settings, Focus, Sleep, and make sure your alarm is set within the Sleep schedule

Android

• Android's Do Not Disturb behavior varies by manufacturer. On stock Android, DND has an Alarms only mode that silences everything except alarms, and a Total silence mode that silences everything including alarms
• On Samsung, go to Settings, Notifications, Do not disturb, and check the Exceptions or Allow exceptions section. Make sure Alarms is set to allowed
• On other Android phones, check Settings, Sound, Do Not Disturb, and look for exceptions or priority settings that control whether alarms can break through
• Scheduled DND is particularly tricky — if DND activates automatically at bedtime and your alarm is set during the DND window, the exception settings determine whether the alarm sounds. Verify the exceptions every time you change DND settings

Fix 3: Check the alarm settings themselves

Sometimes the alarm is configured in a way that prevents it from firing when expected:

• AM vs PM: This is embarrassingly common. If you set the alarm for 7:00 PM instead of 7:00 AM, it will not go off in the morning. Double-check the time and the AM/PM designation. Phones that use 12-hour time format make this mistake easy — switching to 24-hour format in Settings, General, Date and Time eliminates the AM/PM confusion entirely
• Repeat days: If you set an alarm for specific days (Monday through Friday, for example) but today is Saturday, the alarm will not fire. Check the repeat schedule. Also check that the alarm is toggled ON — it is possible to have a configured alarm that is switched off
• Alarm tone: If the alarm tone is set to None or if the selected tone file has been deleted (this happens with custom ringtones that were stored on the phone and later removed), the alarm triggers silently. Go into the alarm settings and select a built-in alarm tone to test. If the alarm fires with sound using a built-in tone but was silent with a custom tone, the custom tone file is the problem
• Snooze behavior: If you snoozed the alarm without fully waking up (a very common occurrence), the alarm did fire — you just do not remember dismissing or snoozing it. The snoozed alarm will fire again after the snooze interval (usually 9 or 10 minutes). If you snoozed it multiple times and eventually dismissed it in your sleep, the alarm functioned correctly but you slept through it. Some alarm apps have a feature that requires you to solve a math problem or scan a QR code to dismiss, which prevents accidental sleep-dismissals

Fix 4: Check battery optimization and app restrictions

This fix applies primarily to Android. Android's battery optimization can put the clock app to sleep, preventing it from firing alarms:

• Go to Settings, Apps, find your Clock app (or the third-party alarm app you use), tap Battery, and set it to Unrestricted (or disable battery optimization for this app)
• On Samsung phones, check Settings, Battery and device care, Battery, Background usage limits. Make sure the clock app is not in the Sleeping apps or Deep sleeping apps list. Apps in these lists are aggressively restricted and may not be able to fire alarms reliably
• On Xiaomi and other Chinese-brand Android phones, battery management is particularly aggressive. You may need to enable Autostart for the alarm app and disable battery optimization in multiple places. Check MIUI's Battery saver settings and App info for the clock app
• Third-party alarm apps are more affected by battery optimization than the built-in clock app. If you use a third-party alarm app and it frequently fails to fire, switch to the phone's built-in clock app for critical alarms — it typically has system-level exemptions from battery optimization

Fix 5: Restart the phone

The alarm service runs as a system process. If this process crashes or hangs (which can happen after an OS update, app conflict, or prolonged uptime), alarms stop firing even though the alarm icon remains in the status bar:

• Restart the phone completely — power off, wait 10 seconds, power on
• After restart, open the clock app, verify your alarm is still set and enabled, and set a test alarm for a few minutes in the future to confirm it fires
• If the test alarm works after a restart, the alarm service had crashed. If this happens repeatedly, check for app conflicts by booting into Safe Mode (Android) — Safe Mode disables all third-party apps, so if alarms work in Safe Mode, a third-party app is interfering with the alarm service

Fix 6: Check the time zone and date

If the phone's time zone is set incorrectly, alarms fire at the wrong time. This commonly happens after travel (the phone connected to a network in a different time zone and switched automatically) or when the automatic time zone setting glitches:

• Go to Settings, General, Date and Time (iPhone) or Settings, System, Date and time (Android)
• Verify the time zone is correct for your location. If Set Automatically is enabled, toggle it off and back on to force a refresh. If the automatic setting keeps choosing the wrong time zone (this happens in areas near time zone boundaries), set the time zone manually

Alarm and notification repair in Marion

Marion Phone Repair diagnoses alarm and notification problems — checking sound settings, Do Not Disturb configurations, battery optimization, and system services to find why alarms and alerts are not sounding.