Syncing an Outlook calendar into Google Calendar

Plenty of people live in two calendars at once. A client runs on Microsoft 365, your own company runs on Google Workspace, and the only place the two meet is in your head — which is exactly where double bookings come from.

There are three ways to put an Outlook calendar onto a Google Calendar grid. They are not equivalent, and the one Microsoft and Google both point you at is the weakest of the three.

Option 1: publish an iCal feed and subscribe to it

Outlook can publish a calendar as an iCal (.ics) URL, and Google Calendar can subscribe to that URL. This is the documented path and it takes about two minutes to set up.

In Outlook on the web, open Settings → Calendar → Shared calendars, pick the calendar under Publish a calendar, choose the permission level, and publish. You get two links; the one ending in .ics is the iCal feed. In Google Calendar, open Other calendars → From URL and paste it.

The catch is refresh rate. Google re-reads a subscribed URL on a schedule it does not publish and you cannot change — in practice, often somewhere between several hours and a day. Subscribed calendars are also read-only on the Google side, so you cannot annotate, recolour or correct anything you see.

Option 2: forward individual invitations

You can also just forward meeting invites from Outlook to your Google address and accept them there. Each accepted invite becomes a real event you fully control.

It works, and for two or three meetings a week it is genuinely the right answer. It does not scale, it misses anything you were not personally invited to, and every change on the Outlook side needs the same treatment again.

Option 3: sync the feed into a calendar you own

The third option keeps the iCal feed as the source but stops treating it as a subscription. Instead of pointing Google at the URL, an add-on reads the feed, works out what changed since last time, and creates, updates or removes matching events in a Google Calendar that belongs to you.

The difference shows up in three places:

That is what ICalSync does. The setup is the same publish step in Outlook; you paste the .ics URL into the add-on instead of into Google’s From URL box, then pick which of your calendars the events should land in.

Getting the Outlook feed URL

The exact menu has moved around over the years. As of now:

1. Outlook on the web → Settings (gear) → Calendar → Shared calendars.
2. Under Publish a calendar, choose the calendar and select Can view all details.
3. Select Publish, then copy the ICS link — not the HTML one.

If your organisation has publishing disabled, this section will be missing or greyed out. That is a Microsoft 365 tenant policy and no calendar tool can work around it; you will need an administrator to enable external calendar publishing.

A note on privacy

An unauthenticated .ics URL is a secret URL: anyone who has it can read the calendar. Treat it like a password, publish the least detail you actually need, and re-publish to rotate the link if it leaks. This applies equally whichever of the three options you pick.

Which one to choose

Forward invites if there are only a handful. Subscribe if you only ever look at the calendar. Sync if the schedule drives decisions and being a few hours behind would cost you something.

The ICalSync setup guide walks through the sync path end to end, and why Google’s iCal refresh is so slow explains what is happening underneath if you want the longer version.