How to Merge Calendars Across Providers

You use Google Calendar for personal events, Outlook for work, and maybe iCloud synced to your phone. But they’re all separate. You miss meetings because you didn’t see a conflict in your work calendar, or you double-book because your personal calendar was on another app. If this sounds familiar, you need to merge your calendars into one view.

There are several ways to do this, each with different trade-offs between cost, effort, and functionality. This guide walks you through all of them so you can pick the right approach for your situation.

Why managing multiple calendars is a problem

When your calendars are scattered across different apps and providers, you lose visibility. Here’s what typically goes wrong:

• Double-booking: Someone books you for a meeting without seeing your personal appointment. You don’t notice until the meeting starts.
• Missed events: You check your Google Calendar but forget you have a work meeting in Outlook. You show up late or miss it entirely.
• Context switching: You have to mentally keep track of which calendar each event is in and switch between apps to manage them.
• Syncing headaches: You edit a meeting in one calendar but forget to update the others. Attendees see conflicting information.

Merging your calendars fixes these problems. When all your events are visible in one place, you can see your full schedule at a glance and manage everything from one app.

Approach 1: Calendar overlay with ICS subscriptions (free, read-only)

Both Google Calendar and Outlook let you subscribe to an external calendar using an ICS (iCalendar) feed. This displays events from one calendar as a read-only overlay in another calendar app. It’s the cheapest option and requires no third-party service.

How it works

An ICS subscription is a one-way, read-only feed. When you subscribe to someone’s calendar or another calendar service, you get a URL that the receiving app polls every 12–24 hours to fetch new events. The subscribed calendar appears in your sidebar alongside your other calendars, and you can toggle its visibility.

Setting it up

Google Calendar to Outlook:

1. In Google Calendar, go to Settings > [Calendar name] > Integrate calendar
2. Copy the Secret address in iCal format
3. In Outlook, go to Add calendar > Subscribe from web
4. Paste the URL and click Import

Outlook to Google Calendar:

1. In Outlook, go to Settings > Calendar > Shared calendars
2. Under Publish a calendar, select the calendar and click Copy link
3. In Google Calendar, click + > From URL and paste it

Limitations

• Read-only — you can see events but can’t edit them from the subscribed view
• Slow updates — refreshes every 12–24 hours, not in real time. A meeting added to Google Calendar won’t show in Outlook for up to a day
• No privacy controls — all event details are visible in full, or nothing is visible. You can’t hide sensitive information
• One direction only — you need to set up the subscription in both directions if you want to see both calendars
• No bi-directional sync — deleting or editing an event in the subscribed view doesn’t affect the original calendar
• Limited on mobile — some mobile calendar apps handle ICS subscriptions differently or not at all

When to use it: You want a free, quick way to check the other calendar without the need for live sync. Good for viewing a spouse’s calendar or a company holiday calendar.

Approach 2: Unified calendar app (Fantastical, Amie, Sunsama)

Apps like Fantastical, Amie, and Sunsama connect to multiple calendar providers and display all your events in a single interface. They don’t actually merge the events into one calendar provider — instead, they show a unified view of all your calendars at once.

How it works

You sign in with your Google, Outlook, and iCloud credentials. The app pulls events from all three providers and displays them in a single calendar view. You can create events in any of your calendars from within the unified app, but the events stay in their original providers.

Advantages

• Unified interface — see all events from all calendars in one place without switching apps
• Easy setup — just sign in with your existing credentials
• Works with any provider — can connect Google, Outlook, iCloud, and many others
• No friction — events stay in their original calendars, so no sync issues or conflicts

Limitations

• Requires a new app — you have to open a third app instead of using your native calendar app
• Only works in that app — if you check your Google Calendar directly, you still don’t see your Outlook events. It’s not a true merge
• Subscription cost — most of these apps charge a monthly or yearly fee (typically $5–15/month)
• Mobile experience — limited on iOS and Android. The web version may be better than the mobile app

When to use it: You want to see all your calendars in one place but don’t want events to actually live in a single provider. Good if you need to keep work and personal calendars separate for administrative reasons but want unified visibility.

Approach 3: Two-way sync with Hetk (real-time, bi-directional)

Hetk connects to your calendar providers via their official APIs and keeps your calendars continuously in sync. Unlike ICS subscriptions or unified apps, Hetk actually syncs events between providers. When you add an event to Google Calendar, it appears in Outlook in seconds. When you edit it in Outlook, the change flows back to Google.

How it works

1. Go to app.hetk.io and sign in with your Google account
2. Add your Outlook account (sign in to Microsoft and grant permissions)
3. Add iCloud or any other provider (if needed)
4. Select which calendars to sync and in what direction
5. Configure privacy settings (mark as private, show as busy only, etc.)

The entire setup takes about 2 minutes. After that, events sync automatically.

Sync mechanics

Hetk uses webhooks and polling to catch every change:

• Google → Outlook: Google sends webhooks immediately when you create, edit, or delete an event. Hetk syncs it to Outlook within 1–3 seconds
• Outlook → Google: Hetk polls Outlook every 30–60 seconds, so updates typically appear within a minute
• Conflict resolution: If you edit the same event in both calendars simultaneously, Hetk keeps the most recent version
• Deletion handling: Deleting an event in the source removes it from the synced copy. The source is authoritative

Key features

• Real-time sync — changes appear in seconds, not hours
• Bi-directional — edit in either calendar and changes flow back. This flexibility is crucial when you actively use both calendars
• Privacy controls — mark synced events as private to hide sensitive details (title, description, location, attendees)
• Identity transform — synced events show your target calendar’s email as organizer, so attendees don’t see the cross-calendar sync
• Duplicate detection — Hetk won’t create duplicates if the same meeting already exists in both calendars
• Sync window — Hetk syncs events from 3 months in the past to 12 months in the future. Older events are ignored to reduce clutter

Privacy features in detail

When you enable Mark as Private, Hetk strips sensitive information:

• Event title becomes “Busy”
• Description and location are removed
• Attendee list is hidden
• Meeting URLs (Zoom, Teams, etc.) are removed

Your coworkers see that you’re unavailable but can’t see what the event is. Free/busy scheduling still works correctly.

Pricing

• Personal ($15/year or $2/month): Up to 3 calendars, unlimited sync relationships
• Professional ($50/year or $6/month): Up to 8 calendars, unlimited sync relationships
• Early adopter pricing: $10/year or $1/month (Personal), $35/year or $3/month (Professional)
• 21-day free trial: Full feature access, no credit card required

When to use it: You actively use multiple calendars and want changes to sync in real time. Best for people who use Google for personal events and Outlook for work, or who manage multiple work calendars.

Approach 4: Consolidate to one provider (nuclear option)

The most straightforward approach is to pick one calendar provider (usually Google Calendar or Outlook) and move all your events there. Once everything is in one place, there’s nothing to sync.

How it works

1. Export events from one provider as an .ics file
2. Import them into your primary calendar
3. Stop using the other calendar
4. Update all your contacts and calendar invites to use your single calendar

Advantages

• No ongoing sync — once events are moved, they stay in one place
• No third-party service — no software to pay for or manage
• Simplest long-term — fewer moving parts means fewer things to break

Disadvantages

• One-time friction — manually exporting, importing, and consolidating can take hours if you have many events
• Losing provider features — if you rely on Outlook-specific features (like Teams integration) or Google-specific features (like Google Meet), you lose them when you switch
• Administrative overhead — if your employer uses Outlook, you may not be able to switch to Google Calendar for work. This approach only works if you have full control over your calendar provider
• Ongoing effort — if you add an event to the wrong calendar later, you have to manually move it

When to use it: You’re starting fresh or willing to do a one-time consolidation. Good if you’re changing jobs or starting a new system. Not practical if you use multiple providers for different purposes.

Comparison table

Which approach should you use?

Quick rule of thumb:

More specific recommendations

If you use Google for personal and Outlook for work: Use Hetk. This is the most common scenario, and Hetk handles it perfectly. You’ll get real-time sync, privacy controls (to keep work events private when synced to personal), and the flexibility to edit in either calendar. The $15/year cost is negligible compared to the time you’ll save avoiding double-bookings.

If you use multiple Outlook calendars (personal + work) or multiple Google calendars: Use Hetk. You can sync between them in either direction, and you get the same real-time sync and privacy features.

If you use Google, Outlook, and iCloud: Use Hetk with selective sync. For example, sync Google ↔ Outlook for daily use, and subscribe to your iCloud calendar as a read-only overlay. This gives you the best of both: real-time sync where you need it most, and a free read-only view of your phone calendar.

If you have a spouse or partner whose calendar you want to see: Use ICS subscription. It’s free and requires no setup. You’ll see their events in your calendar (with a 12–24 hour delay), which is fine for planning purposes.

If you need to consolidate for a job change: Use manual export/import. You’re doing it once, so the manual effort is worth avoiding a new app or service. Once everything is in one calendar, you’re done.

Frequently asked questions

Does Hetk require any special permissions?

Yes, Hetk needs permission to read and create events on your calendars. When you sign in, you’ll grant Hetk access to your Google, Outlook, or iCloud account. Hetk stores your OAuth tokens securely and never sees your password. You can revoke access at any time in your account settings.

Can I sync more than two calendars?

Yes. With Hetk, you can sync Google ↔ Outlook ↔ iCloud in any combination. The Personal plan supports up to 3 calendars, and the Professional plan supports up to 8. You can set up multiple sync relationships (e.g., Google → Outlook, Outlook → iCloud) or create a central hub where everything syncs to one calendar.

What happens if I edit an event in both calendars at the same time?

If you edit the same event in both Google and Outlook simultaneously (before Hetk can sync), Hetk will keep the version that was changed more recently based on timestamps. It’s rare to hit this exact scenario, and when it does happen, you won’t lose data—one version just takes precedence.

Will my recurring events sync?

Yes, Hetk fully supports recurring events. When you sync a recurring event, the entire series syncs. If you edit one instance of a recurring event (e.g., move a single meeting to a different time), Hetk treats it as a separate event and syncs that change. If you modify the entire series, Hetk syncs the entire series change.

Can I sync with the free tier of these calendar providers?

Yes. Hetk works with free Google Calendar accounts, free Outlook.com accounts, and free iCloud calendars. There are no hidden restrictions. The only cost is Hetk’s subscription ($15–50/year), not the calendar providers themselves.

What’s the difference between “private” and “busy” in Hetk?

• Mark as Private strips all event details (title, description, location, attendees) and shows only “Busy”
• Show as Busy keeps all event details but marks the time as “Busy” instead of your original availability (e.g., if the event was “Free”, it shows as “Busy” in the synced calendar)

Use Mark as Private for sensitive personal events you want to hide from coworkers. Use Show as Busy for events you want to be visible but where you want to control how your availability looks.

Can I unsync calendars after I set them up?

Yes. You can delete a sync relationship at any time in your Hetk settings. Events that were synced will remain in both calendars—Hetk won’t delete them. If you want to remove the synced copies, you’ll need to delete them manually. Unsyncing is immediate; it doesn’t take time to process.

Related

• How to sync Google Calendar with Outlook
• Best calendar sync tools in 2026
• Keep work and personal calendars separate