Why didn't my alarm go off?
Key takeaways
- On iPhone, a silent alarm is most often an alarm whose sound is set to None or an alarm volume that is too low. Silent mode and Do Not Disturb do not silence Clock alarms.
- On Android, check Do Not Disturb, Battery Saver, Clock notifications and the alarm volume. Google warns that two alarms set very close together can cancel one.
- Browser alarms only ring while the page is open, visible and unlocked.
- After any change, test with an alarm a few minutes ahead while you are awake.
Why didn't my iPhone alarm go off?
Usually because of the alarm's own sound or volume settings. Apple says Do Not Disturb, the Ring/Silent switch and Silent mode do not affect the alarm sound, so look elsewhere first.
| What happened | What to check (Apple Support) |
|---|---|
| The alarm only vibrated | Clock → Alarms → Edit → the alarm → Sound: make sure it is not set to None |
| The alarm was too quiet | Settings → Sounds & Haptics: raise the alarm volume. On newer iOS, under Alarms and Timers you can turn off Match Ringtone Volume and set it separately |
| The volume keeps changing | Turn off Change with Buttons, so the side buttons do not lower the alarm |
| Headphones were connected | The alarm plays through the built-in speaker as well as the headphones |
| Phone in StandBy | Haptics are off in StandBy, so make sure a sound is selected |
| You changed the clock manually | Apple says setting the time by hand can affect alarms; set the time automatically |
If you use a sleep schedule, its wake-up alarm is listed separately at the top of the Clock app's Alarms tab. Open it and check its sound too, not only your ordinary alarms.
Why didn't my Android alarm go off?
Google's Clock Help lists these causes, and the Clock app may show a message about them:
| Cause | What to do |
|---|---|
| Clock notifications are off | Turn on notifications for the Clock app in Settings |
| Do Not Disturb silenced the alarm | Allow alarms in your Do Not Disturb settings |
| Ringtone set to silent and vibration off | Choose an alarm sound; Google says the alarm will not go off otherwise |
| Volume below 30 % | Raise the alarm volume |
| Battery Saver stopped the alarm | Turn off Battery Saver or add Clock as an essential app |
| Two alarms set close together | Leave at least 5 minutes between alarms, as Google advises |
Phones from different makers have their own clock apps and menus, so the names may differ. The same checks apply.
Why didn't my browser alarm go off?
A web alarm such as HeavySleeper runs inside an open page. It cannot ring if the tab was closed or reloaded, the page was hidden behind another app, the screen locked, the battery ran low, or a power-saving mode paused the browser. It also needs you to tap the page before it may play sound. Keep the page open and visible with the charger in, and always set your phone's own alarm as a backup.
How do I test my alarm properly?
- Set an extra alarm 3–5 minutes ahead, of the same type as the one that failed.
- Put the phone where it is at night, and lock it if that is how you sleep.
- Listen from your pillow. If it is too quiet, adjust and test once more.
- Delete the test alarm afterwards, and check that the real one is still on and set for the right days.
Frequently asked questions
Why did my alarm go off but I did not hear it? It may have been too quiet, too short or a sound you have stopped noticing. Raise the alarm volume, choose a different sound, or add vibration or light; see vibrating alarm clocks.
Do I need to turn off Silent mode on iPhone? No. Apple says the alarm sounds even when Silent mode, Do Not Disturb or another Focus is on.
Can a software update turn off my alarms? Check your alarms after any update: open each one and confirm the time, days and sound.
Sources
- Apple Support. How to set and change alarms on your iPhone.
- Apple. Set an alarm in Clock on iPhone.
- Google Clock Help. Set, cancel, or snooze alarms on your Android device.
Last reviewed 12 November 2026.