Updated
Most mornings, an alarm that fails is annoying. Some mornings it is a missed flight, a missed exam, a missed interview. Those are the mornings you lie awake half checking the clock because part of you does not fully trust the alarm.
That distrust is fair. Alarms rarely fail because they are broken. They fail because a setting on the phone quietly muted them, and none of those settings are visible when you go to sleep. The good news is that the list of things that can go wrong is short, and you can check all of it in a couple of minutes tonight.
Check the volume that alarms actually use
The alarm can be set perfectly and still play too quietly to wake you, because the slider that controls its loudness is not the one you think.
On iPhone, the ringer and alerts volume is separate from media volume. Open Settings, then Sounds and Haptics, and raise the Ringtone and Alerts slider. On Android, alarm volume is its own channel. Open Settings, then Sounds and vibration, then Volume, and raise the alarm slider specifically, not media.
Make sure nothing is set to silence it
A Sleep or Focus schedule you set once can run every night and mute things you did not mean to mute. Alarms are meant to break through, but a third party alarm app that is not allowed to bypass Focus can end up silenced.
Read what is scheduled for tonight, and if you use an alarm app other than the built in clock, confirm it is allowed through.
Full detail: Does Do Not Disturb silence your alarm
Send the sound to the phone, not your earbuds
If AirPods or a Bluetooth speaker are connected, the alarm can play into them instead of the phone speaker. On the one morning that matters, an alarm ringing into a closed case on the nightstand is exactly the failure you cannot afford.
Disconnect earbuds and speakers before bed, and check that audio output is set to the phone.
Full detail: Why your alarm plays through AirPods
On Android, take the app out of battery optimization
Samsung, Xiaomi, and others can stop an alarm app from running overnight to save power, especially after a system update. For an important morning, put your alarm app in the unrestricted or no restrictions battery setting so the system cannot pause it while you sleep.
Full detail: Why your Android alarm stops working
Confirm the obvious two things
Read the alarm one more time and check the day, not just the time. A one off alarm set for today, or repeat days that skip tomorrow, will sit there looking on and never fire. And if the clocks changed recently, confirm the time did not shift by an hour.
Set a second alarm on a second device
For anything you truly cannot miss, do not rely on one phone. Set a backup alarm on a second device, a smart speaker, or a plain clock, at a slightly different time. It is the one habit that survives every setting problem above, because it does not share the same phone or the same failure.
Then you can actually sleep
Every item on this list is invisible the night before. The alarm says on. It looks fine. You find out at the worst possible moment that the ringer was down, or Focus muted it, or the sound went to headphones.
That is the gap Snora closes. Snora is an alarm you set like any other, and before you sleep it checks the settings that can keep your alarm quiet, reading what your phone exposes and walking you through the rest, then shows one status for whether your alarm is set up to go off: Safe, Caution, or Risk. It is a status, not a score to chase, and it is not a promise about your morning, just an honest read that lets you stop half checking the clock all night. The alarm and the check are free, and no account is needed.
For the morning that matters, run the list once tonight, set a backup, and let yourself sleep.
FAQ
Will my alarm still go off if my phone is on silent?
Yes, on both iPhone and Android the alarm keeps its own volume that is separate from the silent or ring switch, so muting the phone does not mute the alarm. What can still make it too quiet is the wrong slider, so raise the alarm loudness the night before: on iPhone under Settings, then Sounds and Haptics, and on Android under Settings, then Sounds and vibration, then Volume, on the alarm channel. Silent mode alone will not stop the alarm, but a lowered slider can leave it too faint to wake you.
Why didn't my alarm go off even though it was set?
Almost always a phone setting muted it rather than the alarm being broken. The usual causes are the ringer or alarm volume turned down, a Focus or Do Not Disturb schedule that silenced it, the sound routed to connected earbuds, or on Android a battery setting that paused the app overnight. None of these show on the alarm screen, so it is worth checking each one before an important morning.
Should I set a backup alarm for an important day?
Yes, for anything you truly cannot miss, set a second alarm on a different device at a slightly different time. A backup on a smart speaker, a spare phone, or a plain clock does not share the volume setting, Focus schedule, or battery state of your main phone, so it holds up even when one of those quietly goes wrong. It is the simplest way to stop relying on a single point of failure.
How can I check all the settings that might mute my alarm at once?
Go through a short list the night before: alarm volume, any Focus or Do Not Disturb schedule, Bluetooth audio routing, and on Android battery optimization, then confirm the alarm day and time. If you would rather not check them one by one, Snora runs that check before you sleep, reading what your phone exposes and walking you through the rest, then shows a single status of Safe, Caution, or Risk for whether your alarm is set up to go off. It is an honest read with no account required, not a promise about how you will wake up.