How to Sync Two Outlook Calendars - 2025 Guide
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Table of Contents
Sync two Outlook Calendars in real-time
In our previous article, we explained in detail how to sync two Google Calendars, highlighting all the steps to ensure they stay in sync.
In this article, we'll explore how to sync two Outlook Calendars, list all the tools and methods, and clear out the misconceptions about calendar synchronization.
When are two Outlook Calendars considered synced?
Two Outlook Calendars are considered synced when they contain the same free/busy availability, even if event details differ. Example: the secondary calendar may anonymize or replace event titles, attendees, or locations to protect the privacy.
Another aspect of calendar synchronization is that both Outlook Calendars should remain in sync, no matter if events get added, updated, or removed in either calendar.
Can I sync two Outlook Calendars by using the Outlook Calendar Sharing Feature?
No, the Outlook Calendar Sharing feature does not sync calendars. The Calendar Sharing Feature in Outlook is meant as a way to share your calendar with your friends, so they can see your availability, but it lacks the ability to directly block time from one calendar to another.
The Calendar Sharing feature in Outlook can also be used to export the calendar via an ics URL, which can be pasted into other Outlook accounts. When you import an Outlook calendar into another Outlook account, the imported Outlook calendar is created as a secondary calendar and has no relation to the primary calendar in that Outlook account.
Outlook Calendar Sync Methods Compared
Let's clear out some misconceptions about calendar syncing, as most articles confuse calendar syncing with calendar sharing, which, as explained above, is not remotely the same thing. The table below compares manual syncing (by hand, copy & paste), calendar sharing and OneCal.
| Method | Reliability | Two-way sync | Privacy controls | Setup time |
|---|---|---|---|---|
| Manual (copy and paste) | Low; easy to miss edits/cancellations | ✗ (manual effort only) | High per-event control, but error-prone | None to start; ongoing effort high |
| .ics import (.ics URL) | Low-medium; delayed refresh, read-only | ✗ (view only, doesn't sync calendars) | Limited; feed often exposes details; no redaction | Low (minutes) |
| Calendar Sync App | High; purpose-built, handles adds/edits/deletes | ✓ | Extensive; can anonymize titles, attendees, locations; mark private | Low (minutes) |
What is the most reliable way to sync two Outlook Calendars?
The most reliable way to sync two Outlook Calendars is to use a calendar synchronization app that connects to multiple Outlook accounts and can keep them in sync.
Our go-to calendar synchronization tool is OneCal, due to its ease of syncing two Outlook Calendars, reliability, and plenty of privacy options.
To sync two Outlook calendars, follow these steps:
1. Sign up for a OneCal Account
OneCal has a two-week free trial plan that allows you to use all the features without any limitations (you can sign up without a credit card).
2. Connect your Outlook Calendars
For this article, we'll connect and sync two Outlook calendars. With OneCal, you can sync as many Outlook calendars as you'd like.
3. Create a new calendar synchronization configuration
A calendar synchronization configuration is just a way to tell OneCal which calendars to sync and what properties to carry over when syncing them. To create a new calendar sync configuration, head over to the “Calendar Sync” tab and click “Start new Sync”
4. Choose multi-way as the calendar synchronization direction
OneCal has one-way and multi-way syncs. For this article, we'll choose multi-way, as it allows us to sync both Outlook calendars both ways. Events in Outlook Calendar 1 will be cloned to Outlook Calendar 2, and vice versa.
5. Select the Outlook Calendars to sync
6. Choose what event properties to sync between calendars
The reason why we recommend OneCal is not only how easy it is to use, but also because of the privacy options it offers. In this step, you can select whether you want to sync event titles, descriptions, attendees, and plenty of other event information.
This is quite useful if your Outlook calendars have sensitive information and you want to anonymize them and only sync the free/busy availability.
Your two Outlook Calendars are synced
OneCal has synced the two Outlook Calendars we selected and will watch for event updates in both calendars and make sure they're reflected appropriately.
Is a calendar synchronization app required to sync two Outlook Calendars?
Microsoft Outlook doesn't have the ability to directly sync events between calendars, so you have to rely on a calendar synchronization app to keep two Outlook Calendars in sync.
Calendar synchronization apps integrate with Outlook Calendar and allow you to directly sync events between them. They're usually able to pick up updates in Outlook Calendar and reflect them accordingly in the other calendars.
Give a read at our article on The Top Calendar Synchronization Apps to learn more about the available apps in the industry, what makes each of them unique, and which one we recommend.
FAQ
Can I sync two Outlook calendars for free?
You can manually keep two Outlook Calendars in sync, but it's not reliable and can lead to scheduling conflicts. Most calendar scheduling apps cost a couple of bucks per month and can save you tons of time and keep scheduling conflicts away.
Will my co-workers see the private event information when syncing two Outlook Calendars?
It depends on the capabilities of the calendar syncing tool you're using. If you use OneCal, you can make the synced events private and strip them of any event information like titles, descriptions, attendees, and only block the time by showing a “Busy” title on all of them.
Will OneCal keep my calendars in sync automatically?
Yes.
What's the difference between one-way and two-way sync?
One-way copies availability from Calendar A to B. Two-way keeps both calendars mirrored so changes in either are reflected in the other.
Will syncing send meeting invitations from the mirrored calendar?
No, OneCal doesn't send invitations to attendees in synced events.
Do recurring meetings work?
Absolutely.
Will I get duplicates or infinite loops?
No, OneCal has complex mechanisms to make sure you don't get infinite loops or event duplicates. Both Outlook Calendars will have the same free/busy events, no duplicates.
Does Outlook's calendar sharing or .ics import count as syncing?
No, it does not. Calendar Sharing shows another calendar's view but doesn't create blocks in your own calendar.