Understand Calendar App Time Zone Support to Avoid Scheduling Mishaps
Every time I travel, I vow to figure out exactly how time zone support works in calendar apps, and every time, I get caught up in whatever I’m doing and forget. Now it’s time to buckle down and see if I can wrap my head around the topic.
I’ll admit to some trepidation about this topic, as I’m uncertain I can even test all the possible scenarios. I’m sure frequent travelers and distributed workgroups have encountered issues that my testing won’t uncover. So, please, if anything I say below doesn’t align with your experience, let me know, and we’ll see if we can figure out why.
Time Zone Issues
The most common issue I encounter when traveling arises when I schedule a 1 PM lunch while I’m at home in Ithaca (Eastern Time), only for the alert to go off at 10 AM when I’m in San Francisco (Pacific Time). I’ve missed meetings at Macworld Expo because the alerts went off three hours earlier than I needed them.
Another issue I’ve encountered, though less frequently, is that when people in different time zones are invited to an event or share a calendar, it’s important to enter events so that they appear at the correct time in each person’s time zone. This usually works well, but if I’m significantly more technical than the other person, I worry that something I’ve done might confuse them.
Adding to the confusion is the fact that Apple’s Calendar app on the Mac includes a checkbox labeled “Turn on time zone support” that lets you pick a time zone for display, while the Calendar app on the iPhone features a Time Zone Override option that allows you to specify a particular time zone. Additionally, calendar apps like BusyCal and Fantastical manage time zone support in slightly different ways. How do these options influence what I see, and do they impact what others will see?
To better understand all of this, I set one of my Macs to Pacific Time (San Francisco), another to Greenwich Mean Time (London), and kept my iPhone on Eastern Time (Ithaca, New York). I created events on each device with their local times included in the title, experimented with toggling time zone support on and off, and switched the Macs between time zones to simulate traveling. Here’s what I concluded.
Events and Reminders Have Time Zones
The key point to understand is that every event has a time zone. All events automatically default to the local time zone, regardless of whether time zone support is enabled. However, if time zone support is turned on, you can manually set an event’s time zone.
Every timed reminder you create in Reminders is assigned to the local time zone, which can lead to confusion while traveling if you depend heavily on reminder alerts. I can’t find options to adjust time zones for reminders in Calendar, Reminders, BusyCal, or Fantastical.
Events may have associated time zones, but how they are displayed depends on two factors:
- The device’s time zone: When you travel to a new time zone, your iPhone, iPad, and Mac typically switch to it automatically, and all event times reflect the change. You can manually reset a device’s time zone, but doing so may cause confusion unless you are troubleshooting or testing. On the iPhone and iPad, you can find this option under Settings > General > Date & Time > Set Automatically. On the Mac, in System Settings > General > Date & Time, you’ll find separate switches for “Set date and time automatically” and “Set time zone automatically using your current location.”
- Calendar app time zone overrides: You can force the Calendar app on your iPhone, iPad, or Mac to act as though it’s in a specific time zone, making all event times reflect the manually selected time zone. On the iPhone or iPad, enable Settings > Apps > Calendar > Time Zone Override. I recommend avoiding this option because it’s buried and thus easy to forget about. On the Mac, go to Calendar > Settings > Advanced, select “Turn on time zone support,” and choose a time zone from the pop-up menu that appears in the upper right corner of the window.
When an event’s time zone differs from the device’s native or manually specified time zone, something will always indicate the difference. For instance, this event was created for 2 PM Eastern Time but is being viewed in Pacific Time; therefore, Calendar displays it at the adjusted time of 11 AM but notes the creation time in parentheses.
Reminders are less obvious. I created a reminder for 4 PM on a device set to Pacific Time. When I view that reminder on a device set to Eastern Time, it shows up at 7 PM in Calendar (left) and Reminders (right), but neither app indicates its original time zone. (The title does, but I did that solely for clarity during testing.)
What About the Floating Time Zone?
While traveling to San Francisco for Macworld Expo, I often encountered the need to juggle multiple meetings each day. I didn’t want to schedule them based on my Eastern time zone because then they’d be at the wrong time once I arrived in San Francisco. At the same time, enabling time zone support and setting them to Pacific Time was tricky since they appeared three hours later on my calendar at home before I left. If I scheduled a lunch meeting for noon on Tuesday, and it showed up at 3 PM, it was all too easy to agree to another lunch that day since noon would seem available.
The answer is the “floating time zone,” which isn’t tied to any specific time zone. Instead, events using the floating time zone appear at the same time regardless of which time zone is currently being observed. The floating time zone first appeared in 1998 in RFC 2445, the specification for the proposed iCalendar standard. Apple seems to be the only major player that has adopted it in a significant way.
The floating time zone is helpful for individuals who are managing their own calendars across multiple time zones and sync between devices using iCloud. If you schedule lunch for noon on Tuesday, it will appear at noon on Tuesday, regardless of where in the world you are.
Unfortunately, the floating time zone isn’t a panacea:
- In Calendar, you can create floating time zone events only on the Mac. For inexplicable reasons, the Calendar app on the iPhone and iPad displays floating time zone events correctly but doesn’t let you create them. The same is true of Calendar in iCloud.com. Both BusyCal and Fantastical allow you to create these events on the Mac and iPhone/iPad.
- Neither Google Calendar nor Microsoft Exchange supports floating time zones, but if you use them only to sync among Apple devices, you might be able to get away with it. As I understand it, editing an event with Google Calendar will switch to a fixed time zone, while Microsoft Exchange will remove the time zone information (which may have roughly the same effect as the floating time zone—I can’t easily test that). Other calendar apps might not support floating time zones correctly, either.
- The floating time zone is appropriate only when you’re traveling between time zones. If you use it to arrange a 4 PM video call with a colleague in a different time zone and you both attempt to join at 4 PM local time, you’ll end up connecting at different times.
- The semi-annual absurdity of Daylight Saving Time adds yet another complication: floating time zone events don’t take into account the fact that local time has sprung forward or fallen back. It’s real governmental inefficiency!
A Few Common Scenarios
I’m sure this isn’t an exhaustive list, but some common scenarios that require thinking about time zones include:
- Traveling to another time zone: When scheduling events for a future trip, you have two options. You can either manually set the event time zone to match the destination or use the floating time zone. Both methods will ensure the events appear at the correct time once you arrive. I prefer the floating time zone because it makes visualizing my schedule on the other end easier before I leave.
- Creating events while away: The same issue arises in reverse if you need to schedule a doctor’s appointment at home, for example, while you’re away in a different time zone. You can manually set the time zone to your home zone or use the floating time zone.
- Dealing with trips through multiple time zones: For complex itineraries, you may want to create events that start and end in different time zones. That’s not possible in the macOS version of Calendar, but it is on the iPhone and iPad, where a Time Zone option appears under both the Start and End time pickers. The Mac version can display such events once created. (Thanks, Jolin!)
- Editing timed reminders manually: Unfortunately, there is no solution for timed reminders. They are always set to their local time zone, which means they will be incorrect in every other time zone. If you depend on regular timed reminders for medications or the like, you’ll need to edit them manually when you arrive at your destination and again when you return home. Apple’s Medications reminders notice time zone changes and ask you what to do with your particular medications (see “An Apple a Day: iOS 16 Medications Feature Provides Alerts, Logging, and Peace of Mind,” 7 October 2022). Consider using the independent reminder app Due for consistent “wall time” reminders (see “Just Due It: Persistent Notifications for Tasks,” 6 July 2024).
- Scheduling calls with distant colleagues: When creating an event and inviting someone in another time zone, you don’t need to do anything special. The event should automatically be set for your local time zone, and when they accept the invitation, it will appear at the correctly adjusted time for their location.
- Shared workgroup calendars: I assume everyone in this situation already knows how to manage time zone-aware scheduling, but once again, creating all events in local time will have the desired effect for everyone viewing a shared event from a different location. However, organizing such events may require more thought, as everyone must determine if they’re available at whatever 10 AM Eastern corresponds to in their local time zone. Numerous websites will help you visualize possible time overlaps; World Time Buddy seemed particularly well-designed.
- Picking a good time for a global webinar: We ran into this back in the Take Control days when we wanted to host live events. Once we settled on a time, we would share an ICS file containing the event details for those who could import it into their calendars. It used our local time zone and adjusted itself for everyone else after import. For those who kept paper calendars or just wanted to know if that time would work for them, the Every Time Zone site does a good job of illustrating how times—and dates—shift around the world.
If you know of any other scheduling situations involving tricksy time zones, please share them in the comments, and I’ll consider adding them.
One possibility is to use “Zulu time” (GMT) which never changes with one’s location or time of year. This removal of ambiguity is the reason it is used in aviation. The only drawback is the need to continually do some simple arithmetic to relate it to the local time. And, of course, you need to always know the offset when traveling.
Just to pick some nits…
You’re actually referring to UTC, which is the conceptual successor to GMT. The term “Zulu” today, refers to UTC, not GMT.
GMT (still used as the local time zone for the UK) actually has summer/winter adjustments, whereas UTC does not.
See also:
Thank you, absolutely right.
I much prefer how iOS handles this compared to my Mac. I have an override for Pacific time on my iPhone. On the Mac I have Time Zone Support set to on and Pacific selected. But when I travel and the Mac detects a new time, the Calendar auto-switches to that and all my entries on calendar get moved around. Then I have to manually go and set it back to Pacific to get things to display the way I want again. It’s not a huge deal, but I’d prefer being able to lock it down on the Mac the way I can on iOS.
I would love to be able to enter a start time in one time zone and end time in another time zone for an event and have it show correctly in the time zone I’m currently in – from booking through to trip end – without manual kludging.
That would be so useful for diarising international travel, eg: booking made in New Zealand today for travel in seven months’ time:
Depart New Zealand at 15:10 New Zealand Daylight Time
10hr 35 min flight time
Arrive Singapore at 21:00 Singapore Time
Transit time in Singapore 4h 25 min
Depart Singapore at 01:25 Singapore Time
13hr 15 min flight time
Arrive Zurich at 08:15 Central European Summer Time
Meetings in Zurich through the day
Depart Zurich 16:30 Central European Summer Time
2hr 20 min flight time
Arrive Dublin 17:50 Irish Standard Time
This type of site can provide this:
Here it converts 1200 Zulu/GMT/UTC on 28 FEB 2025 to a range of local equivalents.
The site also has scheduling tools (so you can determine the “least worst” time for a meeting), etc.
Regards,
Mark
Hi Mark
That’s the site I use to do all the kludging so I can get it into a state to put into Calendar. Having the ability to set different time zones for event start and finish in Calendarwould negate having to do all that converting through time and date.
Cheets, Gobit
I use the web site TripIt for this. For flights, you enter the flight number and it enters the times for you, but you can add the time you leave port in one location and arrive at the other and it figures all of this out for you.
It create a calendar that you can subscribe to in Calendar, Google Calendar, etc. When you arrive at the location the start time automatically shifts to the proper local time, but when I look at my calendar events for a trip I’m taking to France later this year they are now five hours “ahead”.
Of course there is an app as well, but I always enter data on the web site.
There is a pro plan / subscription but all of this basic functionality is free.
Thank you for this article.
Is there a way to have new events default to floating rather than needing to select floating manually?
Got that right, although it could have more emphasis.
FYI…
This complexity is part of why I gave up on digital calendaring and reverted to Filofax. After traveling the world with the military and business for many years (mostly pre-digital) I now live in Europe and have world traveling and living family. I just do the mental calculations and keep World Clocks on my Apple devices. But as a retiree my needs are simple and I sympathize with those who have to deal with this for work and family.
Kudos to @ace for tackling this topic!
Definitely important. This is how travel-booking sites list times on itineraries and is usually the most convenient representation.
Google Calendar’s web interface provides this option:
Definitely a feature Apple should add.
This has always been a problem for me when traveling. It seems that no matter what I try, the time get saved incorrectly. What I resorted to was putting the actual time in the appointment description so I can verify it when I get home. It was a common problem when I was in Central time and trying to schedule something in Eastern time. It looked ok but when I got home the time changed on me unpredictably.
My father, a research scientist (meteorologist), solved this handily. His watch was always set to UTC causing consternation for his kids when they looked at it to find out what time it was.
Dave
That looks a useful site – thanks Doug
Interesting. If Google can surely Apple can
Love it!
Yes! plenty of pilots do the same. Some watches have an extra hour arm or a ring around the outside, and though hard to find there are 24-hour analog watches! Plenty of digital watches can also display at least one other time zone.
This is possible, but for some reason you can only set the different time zones on the iOS/iPadOS versions of Calendar, not the Mac one. Mac Calendar displays them just fine though. It’s a tiny bit hidden, but once you know easy to do.
First, create or edit your event (you can create on the Mac and then edit on iOS to sort out the time zones). You get this display of the start and end times:
Tap on the start time (not the date) and under the dial for setting the time you can set the time zone. This will also set the time zone for the end time:
If you tap the end time, there is also a time zone setting under the dial. If you change this, it will not affect the start time zone. As soon as this is set to a different time zone to the start time, you can see that the relevant time zone code is displayed to the right of the start and end times:
If you tap the end time again, the dial and time zone selector collapse and you can clearly see the start and end times with their respective time zones:
Save this (tap
Done) and you can see the event now reflects the differing time zones for the start and end. The grey text at the top where the date and time are shown shows:So you can use the first line to understand when this is happening in whatever time zone you are currently in, and the second line will correspond to times on train/plane tickets, etc.
You can also see that the coloured block displayed in the calendar day view shows both sets of times: the start and end times of the event in the current time zone and then in brackets the start and end times in the respective time zones with time zone codes:
Although you can’t set separate start and end time zones on Mac Calendar, it also displays them just fine:
Not that I know of. I could imagine an AppleScript that would run regularly and convert everything to floating.
Oh, don’t get me started on that!
OH MY GOODNESS!
Just a tad hidden eh!?
Thank you so very much for taking the time to document this so clearly @jzw. Greatly appreciated.
Cheers, Gobit
Now, if Apple could make it possible to create/edit on the Mac …
I think you can add time zones when using the “Create Quick Event” under the + button on the top Mac Calendar window. I typed in the box, “start on 3/10 2pm pst to 8 pm cst” and it creates a calendar entry from 2-6 pst (my time zone).
Thanks for reminding us of the Create Quick Event box, which does indeed let you specify time zones. However, it may not be quite what @Gobit wants since although you can enter times in two different time zones (whose abbreviations you have to get exactly right—I’m in EDT now, so it wouldn’t accept EST), they’re collapsed to a single time zone when the event is created, though with the correct times.
Couldn’t agree more. I don’t understand why the ostensibly more powerful platform is the one that can’t do this! You’re very welcome, glad I could help.
BusyCal will definitely let you do create an event with Floating as the default on either platform (they recently added the default option for the iOS app).
And I believe Apple’s Calendar.app on the desktop will give you an option to make it default.
Someone wrote a Shortcut you can run on iOS to create a new event that is set to Floating-it’s a little strict on data entry and the iOS interface doesn’t help, but it does work.
Useful tips - thanks Adam and others.
I just entered some flights details and, as advised above, had to use the iPad for entering the appropriate time zones. But they display clearly on the Mac:
I cannot find that option. If you know where it is, please tell me.
As an aside, while poking around Calendar, I found two shortcomings (my opinion) in the Sequoia version. After restarting Calendar, the Settings dialog box does not remember where I last placed it if I had moved it. Also after restarting Calendar, the displayed account under Alerts is On My Mac, even if I had changed it to iCloud in the previous session. Again, it’s my opinion, but this feels like sloppy programming by Apple.
…Mac window management failings rearing its ugly head again, unfortunately.
While improved, many apps’ windows still fail to open where they were left on you chosen Desktop screen after a restart too.
I moved from France to Canada (their Eastern time zone). I still teach students in Germany (UTC +1).
The easiest way to deal with it was to continue to schedule their classes in Kiwi/Gmail Calendar — set to UTC +1 — and have Fantastical mirror that calendar, but set in EST.
Yeah, two calendar apps, but when you have to be awake at teaching class at 02:30 local time, whatever works!
I agree with UTC. It ought to be in use everywhere, then we’d all be on time. My watch (non-smart) is set to UTC.
And we could also use a better calendar: http://hankehenryontime.com/
Ed.
I frequently am in a different continent with a radically different time zone. What I have done for years is keep my laptop set in my home time zone and let my watch and phone adjust to local time (when I started doing this I had to set my watch manually and I didn’t have a phone).
I can view any day in the Calendar app on my laptop and it is in home time, and I can view any day in the Calendar app on my phone and see everything in local time. I find this works well, with the only difficulty being that events in the “floating” time zone alert on my laptop and phone at different times and I need to remember to ignore them on my laptop and only pay attention to them on my phone.
For a few years I lived in a town on Central Time, but work on Mountain Time (out of a railroad terminal whose crews worked west and then back). My watch was always on MT. It was only an hour, but I was still surprised how quickly I habitutated to adjust appropriately.
It’s not that simple! They display correctly on the Mac when you open them in the Calendar—until you click to edit them, then they revert to your local time!! I guess I’ll re-revert to floating.
Edit: I cannot delete the time zone once I’ve added it on the iPhone! “Floating” is not an option!
Adam, while it is not specifically related to time zones, here is my pet peeve about Calendar. I sync my iPhone and iPad calendar to an Outlook calendar on an Exchange server which I view on a Windows machine. If I create an all day event on the iPhone, it shows up in the “all day” portion of the Outlook Calendar, but also shows the entire day, from 12:00 AM to 12:00 PM as being busy. (It is of course not like that on the iPhone.) Opening the all day event in Outlook and turning the “All Day” box off and on resets the event properly - unless someone else has created the event, in which case it can’t be altered. Annoying.
First an enthusiastic endorsement of TripIt. A wonderful app. Not sure you get a lot of (for me) useful stuff with the Pro version, but I would gladly pay a modest subscription for the regular version (say $5-10).
BusyCal does allow Floating Time Zone as a default and it’s great. If I am in Boston, and a friend in Istanbul says, “let’s meet at 1 on Friday” I don’t want to do a lot of calculating. Floating means even that even though I made the entry when I was sitting in Boston, the next day at 30 minutes (or whatever) before 1 in Istanbul, I am reminding to go meet Zeki. People who don’t travel a lot tend to resist Floating Time Zone, and this includes the makers of software. BusyCal was somewhat resistant but one reason I stick with them is that they are very (quickly) responsive to suggestions etc. Hence default floating time zones. Calendar apps would be impossible for me to use if they constantly “corrected” for time zone. What a PITA that is!
I had never heard of floating time zone, but it seems to me this should be the default for reminders if you aren’t going to let people set the time zone for them.