How to Share Google and Outlook Calendar Availability in 2026

Start with the job, not the sync.

Teams say “sync Google and Outlook” when they may mean four different things: see a second calendar, copy events, check free/busy, or schedule a group. Those jobs have different privacy, freshness, and recovery requirements. Picking the wrong one is how a small calendar fix becomes a home-grown distributed system.

• Read-only visibility: show one calendar inside another.
• Event mirroring: copy creates, updates, and deletions between calendars.
• Availability lookup: ask each provider whether a time is busy without copying event content.
• Scheduling execution: coordinate people, collect missing availability, resolve overlap, and send invitations.

Method 1: Subscribe to a published Outlook calendar in Google.

This is the smallest setup. Microsoft lets an Outlook user publish a calendar and choose how much detail people can see. Google can subscribe to the published URL from the “Other calendars” menu.

Publish from Outlook on the web

1. Open Outlook calendar settings and choose “Shared calendars.”
2. Under “Publish a calendar,” select the calendar.
3. Choose the least detail the receiving workflow needs. Free/busy is safer than publishing titles, locations, or descriptions.
4. Publish and copy the ICS link.

Microsoft’s current instructions are in its Outlook calendar sharing guide. The same page says ICS calendars are read-only and that sync frequency depends on the recipient’s email provider.

Subscribe from Google Calendar

1. Open Google Calendar on a computer.
2. Next to “Other calendars,” select “Add other calendars.”
3. Choose “From URL,” paste the published calendar URL, and add it.

Google documents this as a subscription to a published calendar in its calendar subscription guide. It is not a two-way event database. Google edits do not write back to Outlook, and neither provider promises a fixed refresh interval on these pages.

Use it when the stakes are low

A published subscription works for a reference calendar, travel calendar, or other read-only view where a delay will not create a double booking. It is a weak foundation for live booking availability. Treat the URL as a sharing credential, publish the least detail possible, and revoke it when the use case ends.

Method 2: Copy selected events with Power Automate.

Power Automate can connect Office 365 Outlook and Google Calendar. Microsoft’s connector references expose triggers for event creation, updates, and deletion, plus actions for creating, updating, and deleting calendar events.

1. Choose one source calendar and one event trigger.
2. Create the corresponding event in the destination calendar.
3. Store the source and destination event IDs together.
4. Add separate update and delete paths before calling the result a mirror.
5. Add loop prevention, bounded retries, and a reconciliation check for uncertain provider responses.

Start with the official Office 365 Outlook connector and Google Calendar connector. Connector permissions, throttles, trigger behavior, and licensing can change; verify those pages before shipping a business-critical flow.

The trap is simple. A create-event demo looks complete because a copied event appears. The hard cases arrive later: one event is edited, one is deleted, the destination rejects a write, or a retry creates a duplicate. If nobody owns those repair paths, use the flow for a narrow convenience—not as canonical calendar state.

Method 3: Query free/busy instead of copying events.

Product teams often need availability, not event replication. Google Calendar’sFreebusy query returns busy intervals for authorized calendars. Microsoft Graph’s getSchedule operation returns free/busy availability for users and resources over a requested period.

This keeps the data contract closer to the scheduling question: “Is this person available?” It avoids turning every source event into a copied destination event. It does not remove the engineering work around consent, provider identity, time zones, quotas, retries, stale evidence, and the final event write.

Method 4: Coordinate the meeting without forcing a full sync.

Hard meetings cross companies. One organizer may have connected Google availability, a hiring manager may use Microsoft, and a candidate may not want to connect anything. A calendar mirror cannot solve that consent gap.

The scheduling workflow should combine connected free/busy with availability collected directly from anyone who is missing, keep required and optional roles explicit, find the overlap, and send the invitations. Calendar connection helps; it is not the admission ticket for every participant.

WonderCal is the AI-first, conversation-first scheduling execution layer for agents handling hard multi-person, cross-company meetings. See the hard-meeting workflow comparison for the operator view. Developers can also review the released hosted MCP service and its public OAuth evidence. This guide does not infer public REST, OpenAPI, webhooks, SDKs, or an exact MCP tool count.