How to sync Outlook with Google Calendar both ways (two-way sync)

Updated October 2026 · the Calen1 team

In short: Connect your Microsoft 365 and Google accounts in Calen1, pick a two-way pair and you're done: whatever you create, move or delete in Outlook shows up in Google Calendar within minutes, and vice versa, with no duplicates. ICS links and Power Automate can't do this: the first is one-way and read-only; the second means building flows by hand.

Your job lives in Outlook with Microsoft 365 and your life lives in Google Calendar: the dentist, your kid's class, Friday's flight. What you're after isn't peeking from one calendar into the other, it's having them talk both ways: what you schedule, move or delete in Outlook shows up in Google, and what you do in Google shows up in Outlook, with nothing copied by hand.

That's called two-way (or bidirectional) sync, and it's exactly what neither Outlook nor Google offers out of the box. What they do offer (exporting an .ics file or subscribing with an ICS link) goes one way only and is read-only. And when someone wires up a round-trip automation instead, it almost always ends in duplicate events.

This guide explains what syncing both ways really means, why each shortcut falls short, and how to leave a two-way sync running, step by step. It works the same in reverse: work in Google Workspace and personal in Outlook.

What syncing both ways actually means

People use the word “sync” for three different things, and only one of them goes both ways:

• Importing. You copy your events from one calendar to the other once. It's a snapshot: whatever changes afterwards doesn't travel.
• Subscribing (one way). One calendar shows the other's events and re-reads them every so often, but you can't edit them there and nothing you do on that side goes back to the original.
• Syncing both ways (two-way or bidirectional). You create, move or delete an event in Outlook and a few minutes later the same happens in Google; what you do in Google reaches Outlook the same way. Both calendars stay identical without you having to remember anything.

The quick test to see which one you have: create an event in the destination calendar. If it doesn't show up in the original, yours is one-way.

Why Outlook and Google don't do it on their own

Google Calendar and Outlook are two separate systems and neither tells the other anything. It isn't a misconfigured permission: out of the box, they just don't talk. That always produces the same three symptoms:

• Double bookings. You accept something at work without seeing you already had a personal commitment at that time, or the other way round.
• Copying by hand. You end up creating the same event twice. It works until the time changes and you only update one of them.
• Fake availability. Whoever looks for a slot with you sees an incomplete calendar. Your 4pm block doesn't exist as far as they're concerned.

And the more accounts you have (two jobs, outside clients, one account per project), the bigger the hole.

The four DIY fixes, and why they all go one way

Before paying for anything, almost everyone tries one of these four. Three of them are good for something, just not for keeping both calendars identical in both directions.

1. Export an .ics and import it. In Google you go to Settings, Import and export, and download a file; in Outlook you import it. What you get is a frozen snapshot of the moment you exported. Nothing you change afterwards travels, and if you import again to catch up, nothing gets replaced: everything gets duplicated. Fine for a one-time move, not for living this way.

2. Subscribe with the ICS link. Google gives you a secret address in iCal format and Outlook adds it as an internet calendar. It's the best of the options that cost nothing, because it does update on its own. But it's read-only (from Outlook you can't create or edit what comes from Google), Outlook decides when to refresh it and that can take hours, and anyone holding that secret link sees your whole calendar, titles and all. To get both directions you'd need two crossed subscriptions, and each side would still be read-only. Here's the detail on why an ICS link isn't enough.

3. Forward invitations to your other account. It's manual and it only covers events somebody invited you to. Your own blocks (the dentist, deep work, lunch) never travel. And when the organiser moves the meeting, the copy you forwarded stays where it was.

4. Build a round-trip flow in Power Automate (or a similar automation tool). This is where people lose the most time. A typical flow reacts to “an event was created” and makes the copy; for edits and deletions you need more flows, and for the opposite direction, several more. The underlying problem is that the flow doesn't remember which event matches which: the copy it creates in Google triggers the flow that copies from Google to Outlook, and that's how duplicates are born. Recurring series usually land as loose individual copies, and when the connection expires everything stops silently: you find out via a missed meeting.

What a two-way sync has to do to be worth it

The list falls out of the above. Use it to judge any tool, Calen1 included:

• Real two-way: create, edit and delete from either side and have it show up on the other.
• A memory of pairs: knowing that the Outlook event and the Google one are the same thing, so a copy doesn't bounce back and get copied again.
• Reconciliation on connect: if the same event was already on both calendars (say, an invitation that reached both accounts), pairing it up instead of creating a second copy.
• Recurring series as series, not as twenty loose copies you can't edit.
• All-day events and time zones handled properly, especially if you travel or work with another country.
• Privacy: being able to block a slot without revealing what it's for.
• No dependence on you: if you have to press a button every morning, it isn't sync.

Step by step: Outlook and Google Calendar two-way with Calen1

Calen1 joins Google Calendar and Microsoft 365 both ways. The dashboard walks you through four steps and the whole thing takes a few minutes.

1. Start your trial. Pick the Base or Pro plan; the first 5 days are a trial with a card and the first charge is on day six. Cancel before then and you pay nothing.
2. Open your dashboard with a sign-in link sent to your email, or with your Google or Microsoft account.
3. Connect your Google account and allow access to your calendar.
4. Connect your Microsoft 365 account (a personal Outlook.com account works too). Calen1 only asks permission to read and write events.
5. Choose how they join: Two-way. One click creates the pair between your Google primary calendar and your Outlook one. If you'd rather have personal events reach work as “busy” only, choose Privacy (the difference is explained below).
6. Let the first check run. If the same event was already on both calendars, like an invitation that reached both, Calen1 pairs it up instead of duplicating it. Whatever existed on only one side gets copied to the other.
7. Run an honest test. Create an event in Outlook and look for it in Google; change its time in Google and check Outlook; delete it and confirm it disappears from both. Each change shows up on the other side within a few minutes: Calen1 checks your calendars roughly every two minutes, and the dashboard tells you when the last check happened.

A heads-up if you'd been copying by hand: two events you created separately, one on each calendar, are two different events as far as Calen1 is concerned, even if they share a title and a time. Before connecting, delete the manual copies on one side and keep only the original, so you don't end up with the event twice. If it already happened, the guide to duplicate events explains how to clean it up.

From then on, every copy is marked, along with a record of which event it matches on the other side. That's the detail that avoids the classic automation problem: the copy doesn't get copied again.

If you don't want it both ways: one-way or privacy

Two-way isn't always what suits you. In the dashboard's “Calendar merge” section each pair has its own mode, and you can change it whenever you like:

• Two-way: what you create, move or delete in one shows up in the other, and vice versa.
• Google → Microsoft only: Google events are copied to Outlook; Outlook events stay put.
• Microsoft → Google only: Outlook events are copied to Google; Google events stay put.
• Privacy: your Google events show up in Outlook only as busy blocks, at the same time, titled “Ocupado” (Spanish for “busy”): the original title, the description and the location don't travel. It runs one way: delete the event in Google and it disappears from Outlook; delete the “Ocupado” block in Outlook and your original event isn't touched.

Changing modes doesn't restart anything or duplicate anything: if you turn a direction off, the copies it had created are removed on their own within minutes. For privacy in depth, see how to hide personal events on your work calendar.

Several Google accounts, one Outlook (and iCloud)

If you have more than one Google account (your personal one and a project one, say), connect them all: each one forms its own pair with your Outlook calendar, and each pair has its own mode. So that an event born in Outlook doesn't multiply, only one of your Google accounts receives it; the dashboard tells you which.

iCloud connects too, over CalDAV, with an app-specific password you generate at account.apple.com (your normal Apple password is never asked for). Its events land in a new, dedicated calendar called iCloud (Calen1), and you choose whether it runs one way or both. The detail is in the guide to iCloud with Google Calendar.

If you also want people to book you without the email ping-pong

Syncing solves the overlap. What it doesn't solve is the six emails of “does Tuesday work?” only to end up booking Thursday. For that, the Pro plan includes Agenda Pro: your own booking page, which only offers slots that are free across all your connected calendars at once. That's where the sync pays off twice.

• Every booking comes with its Google Meet or Teams link.
• The guest picks their time zone and sees the times in it.
• You decide which calendars count as busy, your hours, the meeting length, the buffers between meetings and the minimum notice for booking.
• It's customised with your logo and your colour.

Pricing and what Calen1 doesn't do (said up front)

Prices are per user, in Mexican pesos: the Base plan costs $50 a month or $500 a year and includes syncing Google, Microsoft 365 and iCloud, privacy mode and multiple accounts. The Pro plan costs $149 a month or $1,490 a year and includes everything in Base plus Agenda Pro. On the annual plan you pay for ten months: two are on the house.

The trial: 5 days with a card. The first charge is on day six and, if you cancel before then, you pay nothing.

The limits, so you don't discover them later:

• Changes take a few minutes to reach the other calendar: Calen1 checks roughly every two minutes. For day-to-day scheduling that's plenty; if you need the copy to appear in the same second, this isn't the tool.
• It's a web application: you open it from the browser, on your phone too. You keep seeing your events in Google Calendar and Outlook as always.
• It only works with calendar events. It doesn't move tasks, contacts or email.
• Today it works with Google, Microsoft 365 and iCloud; other calendar providers, not yet.
• From the dashboard, it joins the primary calendar of each account.

About your data: credentials are stored encrypted; data isn't sold, and it isn't used for advertising or to train artificial intelligence models (Google's Limited Use policy is honoured). You can disconnect any account or delete yours whenever you want.

If all you want is to look at the other calendar now and then, the ICS subscription is enough and you don't need to pay for anything. If you want to write on both sides, have changes and cancellations travel both ways on their own, and stop people booking over you, that's where a two-way sync stops being a luxury.