Guide

Sync Google Calendar with Outlook

Subscribe Outlook to Google Calendar's secret iCal address, and subscribe Google Calendar to Outlook's published ICS URL.

Those built-in subscriptions are one-way. Each app refreshes the feed on its own schedule, and the feed includes whatever event details you published.

Resync is a different tool: it keeps multiple Google calendars from double-booking you by writing private events titled Busy onto the calendars you mark as mirrors.

Built-in option: subscribe with an ICS link

Google Calendar and Outlook can each show the other calendar as a subscribed internet calendar. You copy a feed URL from one app and paste it into the other. This is the native way to put Google events next to Outlook events, or the reverse.

Show a Google Calendar in Outlook

In Google Calendar, open the calendar's settings, then copy the secret address in iCal format.
In the new Outlook, choose Add calendar → Subscribe from web, paste the URL, and import. Microsoft's steps cover new Outlook and a one-time import for classic Outlook.

A subscription is read-only: edits in Outlook do not write back to Google Calendar. Outlook on the web can take more than 24 hours to refresh a subscribed calendar.

Show an Outlook calendar in Google Calendar

In Outlook on the web, open Calendar settings → Shared calendars and publish the calendar. Choose how much detail the link should include, then copy the ICS URL.
In Google Calendar, add it from URL under Other calendars.

Microsoft's publish dialog warns that anyone with the link can view the calendar, and that HTML and ICS calendars are read-only. How often Google fetches that URL is up to Google; there is no refresh interval you can set.

What ICS subscriptions do not do

They are one-way. A booking in Outlook does not create a hold on Google unless you also published Outlook and subscribed Google to that second feed — and even then, each side is still a read-only copy.
Updates are delayed. Microsoft documents waits of more than 24 hours for some Outlook subscriptions. Google Calendar polls subscribed feeds on its own schedule.
Event details travel with the feed unless you published busy-only. Google's secret iCal address is meant to show that calendar in another app, including the events on it.
A one-time ICS import is a snapshot. It does not keep updating. Use a subscription if you want the copy to refresh.

How Resync's Busy holds differ

Resync does not subscribe calendars to each other. It reads when you are busy on Google calendars you mark as sources and writes hold events onto Google calendars you mark as mirrors.

Holds are titled Busy. Description, location, attendees, and conference data are left empty, so source meeting details stay on the source calendar.
When you mark calendars as both source and mirror, a booking on either calendar becomes a Busy hold on the others. That is two-way blocking between those Google calendars.
If a source event moves, Resync updates the hold. If the event is cancelled, marked free, or declined, Resync removes the hold.
Resync currently syncs Google calendars only. It does not write holds into Outlook.

If you need Outlook itself to show a Google calendar, keep the ICS subscription above. Use Resync when the calendars that actually get booked are Google calendars — for example a personal Gmail calendar and a work Google Calendar.

Set up Resync

Sign in with GoogleOpen Resync and sign in with the Google account you want as your primary account. You land on setup.
Connect another Google accountChoose Connect another Google account and finish Google's permission screen. Resync needs at least two Google accounts before you can start.
Start syncingWhen a second account is connected, setup shows bidirectional mirroring as the intended default: real events on either side become private busy blocks on the other. Choose Start syncing to open the dashboard.
Mark sources and mirrorsIn Sync configuration, turn on Source to read busy time from a calendar and Mirror to receive Busy holds. A calendar can be both. Read-only calendars cannot be mirrors because Resync needs write access to create holds.

FAQ

Can ICS keep Google Calendar and Outlook in two-way sync?

No. A subscription is one-way. Outlook can show a Google iCal feed, and Google can show a published Outlook ICS feed, but edits on the subscribed copy do not write back to the source calendar.

How quickly do ICS subscriptions refresh?

Neither app lets you set a reliable refresh interval. Microsoft documents that Outlook on the web and Outlook.com can take more than 24 hours to pick up subscribed-calendar changes. Google Calendar fetches subscribed feeds on its own schedule and does not offer a manual refresh for those feeds.

Do subscribed calendars expose event details?

Usually yes. Google's secret iCal address is meant to show that calendar in another app, including the events on it. Outlook's publish dialog lets you choose how much detail the ICS link includes, from busy time to full event details. Anyone with the published link can subscribe.

Does Resync connect Outlook or Microsoft 365?

No. Resync is a Google Calendar app. It reads busy time from Google calendars you mark as sources and writes Busy holds onto Google calendars you mark as mirrors. To see a Google calendar in Outlook, or an Outlook calendar in Google, use the ICS subscriptions above.

What do Resync Busy holds include?

The hold is titled Busy. Description, location, attendees, and conference data are left empty. Resync does not copy source titles or other meeting details onto the mirror calendar. Free or declined source events do not get a hold. If the source event moves or is cancelled, Resync updates or removes the hold.

What if I delete a Busy hold that Resync created?

Resync records that deletion and does not recreate a hold for the same source event on that mirror calendar.

Connect the Google calendars you want to keep aligned, then mark sources and mirrors on the dashboard.

Resync will ask Google for permission to:see your list of calendars; see events on the calendars you choose as Sources, to know when you're busy; and create, update and delete events titled "Busy" on calendars you choose as Mirrors. We never store event titles, attendees or locations. Privacy policy