The event was in your iPhone calendar, the time came, and no alert ever showed up. When Apple Calendar goes quiet it is almost always a setting, not a bug: the event has no alert, notifications are switched off, a Focus is filtering them, or the alert went somewhere else. Work through the checks below in order and most people are fixed by step four.
The short version: make sure the event has an alert, that Settings > Notifications > Calendar allows notifications with sound, and that no Focus, Silent mode or Scheduled Summary is holding them back.
1. Check the Event Actually Has an Alert
Open the event in the Calendar app and tap Edit. If Alert says None, your iPhone has nothing to show. Pick a time such as 15 minutes before, and add a Second Alert for anything important. Events created by Siri, other apps or invitations from other people often arrive with no alert at all.
2. Set Default Alert Times
New events only get an alert automatically if a default is set. Open Settings > Calendar (on iOS 18 and later, Settings > Apps > Calendar), tap Default Alert Times and choose an alert for Events and All-Day Events. This only applies to new events, so existing ones still need step 1.
3. Allow Calendar Notifications
Turn notifications on. Go to Settings > Notifications > Calendar and switch on Allow Notifications.
Turn on every place they can appear. Tick Lock Screen, Notification Center and Banners, and switch on Sounds. Set the banner style to Persistent if you want it to stay on screen until you deal with it.
Check the alert types. Tap Customize Notifications and make sure Upcoming Events is on.
Keep Time Sensitive on. Make sure Time Sensitive Notifications is enabled for Calendar, so event alerts can break through a Focus.
4. Check Focus, Do Not Disturb and Sleep
A Focus is the most common reason alerts appear in Notification Center but never light up the screen or make a sound. Open Settings > Focus, and for each Focus you use (Do Not Disturb, Work, Sleep, Driving) tap Apps and add Calendar to the allowed list, or turn on Time Sensitive Notifications. Remember a Focus can switch on by itself on a schedule, at a location, or when you open an app.
Watch out: Focus settings sync across your Apple devices. Turning on Do Not Disturb on your Mac can silence your iPhone too. Check Share Across Devices at the bottom of the Focus screen.
5. Turn Off Silent Mode and Check the Alert Sound
With Silent mode on, calendar alerts still appear but make no sound, which is easy to miss with the phone face down. Turn it off with the Ring/Silent switch or the Action button. Then open Settings > Sounds & Haptics > Calendar Alerts and make sure the tone is not set to None, and that the ringer volume is turned up.
6. Take Calendar Out of Scheduled Summary
If you use Scheduled Summary, any app in it delivers its notifications in a batch at set times instead of immediately. Go to Settings > Notifications > Scheduled Summary and make sure Calendar is switched off in the list of apps. A 9:30 alert that waits for a 12:00 summary is no alert at all.
7. Check Your Apple Watch
When you wear an Apple Watch and your iPhone is locked, notifications go to the watch instead of the phone. If the watch is on a charger, in a drawer, or set to silent, the alert can seem to vanish. Open the Watch app on your iPhone, tap Notifications > Calendar and choose Mirror my iPhone, or set up custom alerts so you notice them on the wrist.
8. Fix Synced Google, Outlook and Exchange Calendars
If your events live in Google, Outlook or a work Exchange account, they only alert if they reach your iPhone before the alert time.
Make sure the account syncs calendars. Open Settings > Calendar > Accounts (on iOS 18 and later, Settings > Apps > Calendar > Calendar Accounts), tap the account and check that Calendars is switched on.
Do not use Manual fetch. In Fetch New Data, turn on Push where available, or set a short fetch interval. With Manual, events added on your computer may not appear until you open the Calendar app.
Check the calendar is visible. In the Calendar app tap Calendars at the bottom and make sure the calendar is ticked.
Remember alerts do not always sync. An alert you set in Google Calendar on the web is not always carried over to Apple Calendar. If in doubt, open the event on your iPhone and check step 1.
If you also see the problem in the Google or Outlook apps themselves, our guides to Google Calendar notifications not working and Outlook calendar notifications not working cover those apps.
9. The Usual Last Resorts
If everything above looks right, restart your iPhone, install the latest iOS update in Settings > General > Software Update, and check Settings > Calendar > Time Zone Override: if it is on and set to a different city, alerts will fire at the wrong time. Low Power Mode can also delay background sync for Google and Outlook accounts.
Quick Checklist
| Symptom | Most likely cause | Fix |
|---|---|---|
| No alert for one event | Event alert set to None | Edit the event and add an alert |
| New events never alert | No default alert time | Set Default Alert Times |
| No alerts at all | Calendar notifications off | Settings > Notifications > Calendar |
| Alert in Notification Center only | Focus or Do Not Disturb | Allow Calendar in each Focus |
| Alert shows but no sound | Silent mode or tone set to None | Turn off Silent mode, set a Calendar Alerts tone |
| Alerts arrive in a batch | Scheduled Summary | Remove Calendar from the summary |
| Alerts seem to vanish | Sent to Apple Watch | Check Watch app > Notifications > Calendar |
| Google or Outlook events silent | Sync off or Manual fetch | Turn on Calendars and Push for the account |
When a Notification Is Not Enough
Even with every setting right, a calendar alert is a banner and one short sound. It is easy to miss with your phone in a bag, face down on a desk, or in another room. That is the limit of notifications, not a settings problem; we explain why in why calendar notifications fail.
For events you cannot afford to miss, the Remindavo iPhone app turns each event into a full-screen incoming call, even when your phone is locked, with a voice that reads the event name: "Dentist appointment in 30 minutes." It reads the calendars already on your iPhone, including iCloud, Google, Outlook and Exchange, so moved and new events are picked up automatically.
Install Remindavo from the App Store via remindavo.com/mobile-app.
Allow calendar access and pick the calendars you want calls for.
Choose how early you want the call and verify your phone number.
The free plan includes 5 real reminder calls or 14 days, whichever comes first, with no credit card. More on the setup is in our guide to phone call reminders for Apple Calendar, and for one-off reminders see how to set a reminder on iPhone.