Alarm volume confuses people because it behaves differently from every other sound on the phone, and because the most obvious control, the side buttons, usually does not affect it.
Where alarm volume actually lives
Settings → Sounds & Haptics → Ringtone and Alerts. That slider controls alarms and the ringer together. Drag it up and your alarm gets louder.
Below it is Change with Buttons. When off, the side buttons only change media volume, so turning your music down at night does not quieten tomorrow's alarm. When on, the side buttons change the ringer and alarm too, which is how people accidentally silence themselves.
If you have ever turned the volume down while watching something in bed and then had a quiet alarm, this setting is why.
The silent switch does not mute alarms
Worth stating clearly, because it is the most common misconception. Silent mode silences the ringer and notifications. Alarms are exempt, by design, and always have been. The same applies to Focus modes including Sleep Focus.
So if your alarm was quiet, it was not silent mode. It was the volume slider, or something physical.
Physical things that make alarms quieter
- A soft surface. A phone on a mattress, duvet or fabric-topped nightstand is dramatically quieter than the same phone on wood or glass. This makes more difference than most people expect.
- Face down on soft material, which muffles the speaker directly.
- Under a pillow or in a drawer.
- A blocked or dusty speaker grille. Worth a look if everything has got quieter over time.
- Connected Bluetooth. If headphones or a speaker are still paired and in range, check where the sound is actually going.
- A case covering the speaker ports.
The cheapest upgrade available: put the phone on a hard surface, across the room. Louder and further away, both of which help.
Why louder usually is not the answer
If you are waking up and switching the alarm off without remembering, the alarm was already loud enough to rouse you. The failure happened after that, at the dismissal, and volume does nothing about it.
Volume only helps if you genuinely are not being woken at all, and in that case the more likely cause is sleep debt rather than decibels. More on which failure you have in what to do when the iPhone alarm is not enough.
Alarm tone matters more than volume
A tone with sharp changes in pitch and rhythm is harder to sleep through than something smooth at the same volume, which is why traditional alarm sounds are unpleasant on purpose. Apple's Clock lets you choose from a full library and use your own audio.
Mornio deliberately does not offer custom tones and uses the standard iOS alarm sound. When we tested custom tones they stopped after a few seconds while the system tone kept ringing continuously, so we chose the one that keeps making noise. It is a real limitation, and if choosing your own tone matters to you, Apple's Clock or Alarmy will serve you better.