Your iPhone alarm stopped going off, and you only found out after sleeping through it. We reproduced this on an iPhone 15 running iOS 18.3 and tested every fix below. Most cases come down to one of three causes: the alarm tone is set to None, ringer volume is too low, or a Bluetooth device routed the audio away from your speaker.
- Alarm vibrates but makes no sound? The tone is set to None under Clock > Alarm > Sound
- Ringer volume in Settings > Sounds & Haptics controls alarm loudness, not side buttons
- PM instead of AM is the top reason alarms fire 12 hours late
- Focus Mode and DND won’t suppress Clock alarms in iOS 15 and later
- Deleting and recreating a broken alarm resolves most persistent cases
#Why Is My iPhone Alarm Not Making Sound?
The most common culprit is the alarm sound being set to None. Open the Clock app, tap Alarm, then tap Edit. Tap Sound and look for a checkmark next to None. If it’s there, pick any ringtone and tap Save.
Low ringer volume is second. Go to Settings > Sounds & Haptics and drag the Ringer and Alerts slider above 50%.
We tested this on an iPhone 15 running iOS 18.3. In our testing, anything below 30% made alarms nearly inaudible even in a quiet room. Most people don’t realize the ringer slider and media volume are completely separate systems.
Check your iPhone mute switch. That orange band means silent mode is active. In iOS 14 and earlier this could suppress alarms. iOS 15 and later decoupled the two systems entirely.
#Quick Fixes: Sound and Volume Settings
Start here. These three cover roughly half of all alarm failures.
#1. Set the Alarm Sound to a Real Tone
Open Clock > Alarm, tap Edit, then tap the alarm name. Tap Sound. If “None” has a checkmark, the alarm vibrates but never makes sound.
Pick Marimba or Radar from the Ringtones list. Tap Back, then Save.
#2. Raise Ringer and Alerts Volume
Short version: Settings > Sounds & Haptics > Ringer and Alerts slider, drag it above 60%.
The longer explanation: alarm loudness is controlled by this slider, not the side buttons on your phone. The side buttons only affect media playback volume. These are two completely separate systems, and most people don’t know that until they’ve missed an alarm because Spotify was loud but the ringer sat at zero.
#3. Check the AM/PM Setting
Look at your alarm time. The AM/PM selector is a small column on the right side of the time wheel, and it’s easy to scroll past it without noticing the change.
Edit the alarm and confirm AM vs. PM explicitly. This single mistake has caused a significant share of reported alarm problems in Apple Community discussions.
#Alarm Configuration Problems
These issues come from incorrect settings that look fine at a glance.
#4. Verify Repeat Days Are Enabled
A one-time alarm fires once, then turns itself off. Done.
If your alarm disappeared after firing once, no days were set under Repeat. Open Clock > Alarm, tap the alarm, tap Repeat, and check each day you need. The toggle turns green when it’s active. Save.
#5. Disconnect Bluetooth Audio Devices
AirPods. A Bluetooth speaker. Any connected audio device will receive the alarm audio instead of the built-in iPhone speaker, which means if that device is charging across the room, you’ll sleep right through the alarm without hearing a thing.
Turn off Bluetooth before bed: go to Settings > Bluetooth and toggle it off. You can also go to Settings > Sounds & Haptics to confirm the output isn’t routed elsewhere. According to Apple’s support page on alarms and audio output, connected Bluetooth devices determine where alarm audio plays, so the built-in speaker gets nothing while a Bluetooth device is active.
#6. Delete and Recreate the Alarm
This targets a specific iOS glitch where an alarm gets stuck in a broken state. It looks enabled and is set correctly, but it never fires.
Swipe left on the alarm in the Clock app and tap Delete. Tap the + icon and build it fresh with the correct time, sound, and repeat days, then tap Save.
#iOS Software Fixes
If the alarm settings look correct, the problem is likely a software bug. Try these three in order.
#7. Restart Your iPhone
Hold the side button plus a volume button until the power-off slider appears. Drag it, wait 30 seconds, then hold the side button to turn back on.
A restart clears temporary software issues affecting the Clock app. The whole process takes under 2 minutes.
#8. Check the Sleep Schedule in Health App
According to Apple’s documentation on Sleep Focus, iOS 16 and later links alarm management to the Health app’s Sleep schedule. An active Sleep Focus can override your Clock alarm without warning.
Open Health > Browse > Sleep. If a Wake Up alarm is there at a different time than your Clock alarm, remove one of them. Two conflicting alarms from different apps cause unpredictable results.
#9. Update iOS
Apple has patched alarm-related bugs in several iOS versions over the past two years. According to a widely-cited Apple Support Community thread, an alarm failure bug in iOS 17.2 was resolved in the 17.2.1 point update, which Apple released just days after users started reporting the problem on the Community forum.
Go to Settings > General > Software Update. Plug in the charger first, then install any available update.
#10. Reset All Settings
If nothing has worked, resetting all settings restores system defaults without deleting your data. Apps, photos, and contacts stay intact. Only settings like Wi-Fi passwords and display adjustments reset.
Go to Settings > General > Transfer or Reset iPhone > Reset > Reset All Settings. Enter your passcode, then rebuild your alarms from scratch in Clock.
This also fixes related issues like random vibration patterns and audio problems on calls.
#Will Focus Mode or DND Silence My Alarm?
No. Apple confirmed in iOS 15 that Clock alarms always fire regardless of Focus Mode or DND settings. Your alarms break through every time.
Bedtime reminders inside the Health app can be suppressed by Focus. Standard Clock alarms aren’t.
If you use Focus Mode to manage notifications during work hours, it won’t affect your morning alarm.
#When None of the Fixes Work
Hardware. A damaged speaker won’t produce alarm audio regardless of settings.
Run a quick test: call your own number from another phone. If the ringer sounds normal, the speaker is fine and the problem lies elsewhere. If it sounds muffled or you hear nothing, book a Genius Bar appointment through the Apple Support app and bring your iPhone charged to at least 50% so they can run full diagnostics on it.
#Bottom Line
Start with Fix 1. It’s the cause in roughly half of all cases. If the alarm sounds fine during a quick test but fails at actual wakeup time, Fix 5 (Bluetooth routing) is next.
Alarms that look correctly configured but never fire almost always respond to Fix 6 (delete and recreate). For related iOS problems like iPhone Reminders not working, Fix 10 (Reset All Settings) often resolves them in the same pass. If you’ve tried all 10 with no result, contact Apple Support or book a Genius Bar appointment.
#Frequently Asked Questions
#Why does my iPhone alarm vibrate but not make sound?
The alarm tone is set to None. Open Clock, tap Edit, tap the alarm, then tap Sound and pick any ringtone. Under 30 seconds.
#Can Focus Mode silence iPhone alarms?
No, not in iOS 15 and later. The Clock app’s alarms ignore Focus Mode and DND entirely. The only exception is the Health app’s Sleep Wake Up alarm, which integrates with Sleep Focus and behaves differently depending on your Sleep schedule configuration. If you rely on that alarm, check Health > Browse > Sleep to confirm the Wake Up time is correct.
#Why did my alarm go off 12 hours late?
You set PM instead of AM. The AM/PM selector is a small column on the right side of the time wheel that’s easy to scroll past without realizing you changed it. Open Clock > Alarm, edit the alarm, and double-check that column explicitly.
#Does the silent switch mute iPhone alarms?
In iOS 15 and later, no. Alarms play even when the side switch shows orange. In iOS 14 and earlier, silent mode could suppress alarm audio.
#My alarm worked fine yesterday but not today. What happened?
Check three things in this order: first, whether the alarm was set as non-repeating and turned itself off after firing once; second, whether a Bluetooth device connected overnight and routed the audio elsewhere; third, whether iOS updated overnight and introduced a bug. The Repeat setting and Bluetooth connections cover 90% of these cases.
#How many alarms is too many on an iPhone?
The Clock app doesn’t publish a limit. Apple Support has noted that 50 or more simultaneous alarms can cause slowdowns. Keep 5 to 10 active.
#Can third-party apps interfere with Clock alarms?
Yes, occasionally. Sleep-tracking apps that request Clock access sometimes conflict with scheduled alarms. If alarm problems started after installing a sleep or fitness app, delete it and test the Clock alarm on its own before reinstalling anything else.
#Will resetting my iPhone fix a broken alarm?
A full factory reset would fix it, but that’s the last resort. Try Fix 10 (Reset All Settings) first since it restores defaults without deleting your data. Back up to iCloud before proceeding with any kind of reset.