You add an appointment on your Mac, check your iPhone later, and it’s nowhere to be found. Your calendar events seem to live separate lives on each device. This happens more often than you’d think, and it’s frustrating when you need your schedule to match up everywhere.
We’re going to walk through why your Calendar app refuses to sync between your Mac and iPhone. You’ll learn what causes this hiccup and how to get your devices talking to each other again.
What’s Really Happening With Your Calendar
Calendar syncing between your Mac and iPhone relies on iCloud to keep everything updated. When you create an event on one device, iCloud should instantly send that information to all your other devices signed in with the same Apple ID. This happens behind the scenes without you lifting a finger.
But sometimes this smooth process hits a snag. Your Mac might save an event locally instead of sending it to iCloud. Your iPhone could be using a different calendar account. Maybe your internet connection dropped right when you added that doctor’s appointment.
The result is the same: your calendars show different information on each device. You might see old events on your iPhone that you already deleted on your Mac. Or worse, you could miss an important meeting because it only showed up on one device.
Here’s what makes this problem tricky. Your devices might look like they’re working fine. The Calendar app opens, you can add events, everything seems normal. But that sync feature is quietly broken in the background, and you won’t notice until you check your schedule on a different device.
Calendar on Mac Not Syncing With iPhone: Likely Causes
Several things can break the sync between your Mac and iPhone calendars. Let me walk you through what usually goes wrong so you can spot the issue faster.
1. iCloud Calendar Is Turned Off
Your Calendar app won’t sync if iCloud Calendar isn’t active on both devices. Each device has its own iCloud settings, and they need to match up.
On your Mac, you might have accidentally toggled off the Calendar option in System Settings. Your iPhone could have the same setting disabled. Either way, iCloud can’t do its job if it’s not allowed to touch your calendar data.
This happens a lot after software updates. Sometimes an update resets your iCloud preferences, turning off features you had enabled before. You assume everything still works the same, but that one setting got switched off.
2. Different Apple IDs on Each Device
Using separate Apple IDs on your Mac and iPhone stops calendar syncing dead in its tracks. iCloud only syncs data between devices signed in with the same account.
Maybe you set up your Mac with a work email years ago and your iPhone with a personal one. Or perhaps you share a Mac with family members who use different accounts. These situations create separate iCloud environments that can’t talk to each other.
3. Poor Internet Connection
Calendar syncing needs a stable internet connection to work. Your Mac or iPhone can’t send updates to iCloud if they’re offline or dealing with a weak signal.
Picture this: you’re at a coffee shop with spotty WiFi, and you add a meeting to your Mac calendar. Your computer tries to sync but keeps failing because the connection drops. Later, you’re out of WiFi range on your iPhone with no cellular data, so it can’t receive the update even if your Mac eventually sent it.
These connection issues stack up over time. Each failed sync attempt creates a bigger gap between what your devices know about your schedule.
4. Calendar Account Settings Are Wrong
Your Calendar app can pull events from multiple sources like iCloud, Google, Exchange, or other accounts. If your events are saved to the wrong account, they won’t sync through iCloud.
This gets confusing fast. You might create an event thinking it goes to your iCloud calendar, but it actually saves to a local calendar on your Mac. That event stays trapped on that one device because local calendars don’t sync anywhere.
Sometimes the Calendar app picks a default calendar that isn’t your iCloud one. You won’t notice unless you check which calendar each event belongs to.
5. Outdated Software
Running old versions of macOS or iOS can cause sync problems. Apple regularly fixes bugs and improves how devices communicate with iCloud.
An outdated Mac might use an older sync method that your updated iPhone doesn’t understand properly. Or your iPhone could have new features that your Mac’s Calendar app can’t process. These mismatches lead to events getting stuck or disappearing.
Software updates also patch security issues that might affect iCloud connections. Skipping updates leaves these problems unresolved.
Calendar on Mac Not Syncing With iPhone: How to Fix
Getting your calendars to sync again usually takes just a few quick adjustments. Here’s what you need to try.
1. Check Your iCloud Calendar Settings
Start by making sure iCloud Calendar is turned on for both devices. This is the most common fix and takes less than a minute.
On your Mac, go to System Settings, click your name at the top, then select iCloud. Look for Calendar in the list and make sure it has a checkmark. If it’s off, click to turn it on.
For your iPhone, open Settings, tap your name, select iCloud, and scroll down to Calendar. Toggle it on if it’s off. Your iPhone might take a few seconds to start syncing after you enable this.
Give both devices a couple of minutes to catch up. Check if new events you create now appear on both devices.
2. Verify You’re Using the Same Apple ID
Both devices need to use the same Apple ID for iCloud syncing to work. Mismatched accounts are a quick way to break the connection.
On your Mac, check System Settings, click your name, and look at the Apple ID email shown. Write it down. Then grab your iPhone, open Settings, tap your name at the top, and compare the email address.
If they’re different, you’ll need to decide which Apple ID you want to use for your calendars. Sign out of iCloud on one device and sign back in with the matching Apple ID. Keep in mind this might affect other iCloud data like photos or documents, so back up anything important first.
3. Restart Both Devices
A simple restart clears out temporary glitches that might block syncing. Your Mac and iPhone refresh their connections to iCloud when they boot up again.
For your Mac, click the Apple menu and choose Restart. Let it shut down completely and start back up. On your iPhone, hold the power button (and volume button on newer models) until you see the power slider. Swipe it, wait for the phone to turn off, then press the power button again to restart.
After both devices restart, open the Calendar app on each one. Create a test event on your Mac and see if it shows up on your iPhone within a minute or two.
4. Check Your Default Calendar Account
Make sure your events are saving to your iCloud calendar, not a local one that doesn’t sync.
Open Calendar on your Mac and create a new event. Before you save it, look for a Calendar dropdown menu in the event details. This shows which calendar will store your event. If it says something like “On My Mac” instead of “iCloud,” that’s your problem.
Change the default by going to Calendar > Settings > General and setting your iCloud calendar as the default. On your iPhone, go to Settings > Calendar > Default Calendar and pick your iCloud calendar there too.
From here on out, your new events will save to the right place and sync properly.
5. Toggle iCloud Calendar Off and On
Sometimes iCloud needs a reset to start syncing again. Turning the Calendar feature off and back on forces your devices to reconnect.
On your Mac, go to System Settings > Your Name > iCloud, uncheck Calendar, wait about 10 seconds, then check it again. Do the same on your iPhone through Settings > Your Name > iCloud. Toggle Calendar off, pause, then toggle it back on.
This method often kicks stubborn sync issues loose. Your devices re-establish their connection to iCloud’s servers and download any missing events.
6. Update Your Software
Keeping your Mac and iPhone updated fixes bugs that cause sync problems. Apple releases patches specifically for issues like this.
On your Mac, click the Apple menu, choose System Settings, then General > Software Update. Install any available updates. For your iPhone, go to Settings > General > Software Update and do the same.
Updates can take a while to download and install, so start this when you have time. Your devices might restart during the process, which is normal.
After updating, test your calendar sync again. Create an event on one device and check if it appears on the other.
7. Contact Apple Support
If you’ve tried everything and your calendars still won’t sync, reach out to Apple Support. They have tools to diagnose deeper iCloud issues that you can’t fix on your own.
Apple’s support team can check if there’s a problem with your iCloud account or if something unusual is blocking the sync. They might spot settings you missed or identify a rare bug affecting your devices. You can contact them through the Apple Support app, their website, or by visiting an Apple Store.
Wrapping Up
Calendar sync issues between your Mac and iPhone usually come down to a few simple settings that got switched off or configured wrong. Most of the time, checking your iCloud settings and making sure both devices use the same Apple ID solves everything.
Keep your software updated and pay attention to which calendar account you’re using for new events. These small habits keep your schedule flowing smoothly between all your devices. Your calendar works best when it’s actually in sync, and now you know exactly how to keep it that way.