You use Google Calendar for personal events, Outlook for work, maybe iCloud on your phone. But they’re separate. You miss meetings because a conflict was only in your work calendar. You double-book because you didn’t check all three.
This guide covers four ways to merge them, with different trade-offs on cost, effort, and speed.
Why multiple calendars are a problem
Scattered calendars mean lost visibility. Here’s what goes wrong:
- Double-booking — someone books you without seeing your personal calendar. You don’t notice until the meeting starts
- Missed events — you check Google but forget about Outlook. You show up late or miss it
- Context switching — you mentally track which event is where and jump between apps
- Sync chaos — you edit one calendar but forget to update the others. Attendees see different information
When all events are visible in one place, you see your full schedule and manage everything from one app.
Approach 1: ICS subscriptions (free, read-only)
Both Google Calendar and Outlook let you subscribe to external calendars via ICS (iCalendar) feeds. It’s read-only, cheap, and requires no third-party service.
How it works
An ICS subscription is a one-way, read-only feed. You get a URL that the app polls every 12–24 hours for new events. The subscribed calendar appears in your sidebar.
Setting it up
Google Calendar to Outlook:
- In Google Calendar, go to Settings > [Calendar name] > Integrate calendar
- Copy the Secret address in iCal format
- In Outlook, go to Add calendar > Subscribe from web
- Paste the URL and click Import
Outlook to Google Calendar:
- In Outlook, go to Settings > Calendar > Shared calendars
- Under Publish a calendar, select the calendar and click Copy link
- In Google Calendar, click + > From URL and paste it
Limitations
- Read-only — you can’t edit events from the subscribed view
- Slow updates — refreshes every 12–24 hours
- No privacy controls — it’s all details or nothing
- One direction only — you need two subscriptions to see both calendars
- No edits sync back — changes in the subscribed view don’t affect the original
- Limited on mobile — some apps handle ICS subscriptions differently
Best for: Viewing a spouse’s calendar or company holiday schedule for free. Not for active sync.
Approach 2: Unified calendar app (Fantastical, Amie, Sunsama)
Apps like Fantastical and Amie connect to multiple calendar providers and show all your events in one interface. They don’t merge events into one provider, just show everything at once.
How it works
You sign in with your Google, Outlook, and iCloud credentials. The app pulls events from all three and displays them in a single view. You can create events in any calendar from within the app, but they stay in their original providers.
Advantages
- Unified interface — see all events in one place without switching apps
- Simple setup — just sign in with existing credentials
- Works with any provider — Google, Outlook, iCloud, and others
- No sync friction — events stay where they are, no sync issues
Limitations
- Requires a new app — you have to open a third app instead of using your native calendar
- Not a true merge — if you check Google Calendar directly, you still don’t see Outlook
- Subscription cost — typically $5–15/month
- Mobile experience — limited on iOS and Android
Best for: Seeing all calendars in one place without keeping them separate administratively. Good if you need unified visibility but want to maintain work/personal separation.
Approach 3: Real-time sync with Hetk (bi-directional)
Hetk connects to your calendar providers via their official APIs and syncs events between them. When you add an event to Google Calendar, it appears in Outlook in seconds. Edit it in Outlook, and the change syncs back.
How it works
- Go to app.hetk.io and sign in with your Google account
- Add your Outlook account (sign in to Microsoft and grant permissions)
- Add iCloud if needed
- Select which calendars to sync and in what direction
- Configure privacy settings if you want to mark events as private
The whole setup takes about 2 minutes. After that, events sync automatically.
Sync mechanics
Hetk uses webhooks and polling:
- Google → Outlook: Google sends webhooks immediately. Hetk syncs within 1–3 seconds
- Outlook → Google: Hetk polls every 30–60 seconds, updates appear within a minute
- Conflicts: If you edit the same event in both calendars at once, Hetk keeps the most recent version
- Deletions: Deleting an event in the source removes it from the synced copy
Key features
- Real-time — changes appear in seconds
- Two-way — edit in either calendar and changes sync back
- Privacy controls — mark events as private to hide sensitive details
- Identity transform — synced events show your target calendar’s email as organizer
- No duplicates — Hetk won’t create duplicates if the same meeting exists in both calendars
- Sync window — events from 3 months past to 12 months future
Privacy controls
When you enable Mark as Private, Hetk strips information:
- Title becomes “Busy”
- Description, location, meeting URLs are removed
- Attendee list is hidden
Coworkers see you’re unavailable but can’t see what the meeting is. Free/busy scheduling still works.
Pricing
- Personal ($15/year or $2/month): Up to 3 calendars
- Professional ($50/year or $6/month): Up to 8 calendars
- Early adopter: $10/year or $1/month (Personal), $35/year or $3/month (Professional)
- 21-day free trial: Full feature access, no credit card
Best for: Actively using multiple calendars with real-time sync. If you use Google for personal and Outlook for work, this is the fit.
Approach 4: Consolidate to one provider
Pick one calendar provider (Google or Outlook) and move all your events there. Once everything is in one place, there’s nothing to sync.
How it works
- Export events from one provider as an .ics file
- Import them into your primary calendar
- Stop using the other calendar
- Update your contacts and calendar invites to use your single calendar
Advantages
- No ongoing sync — events stay in one place
- No third-party service — nothing to pay for or manage
- Simple long-term — fewer moving parts
Disadvantages
- One-time effort — exporting, importing, and consolidating takes hours with many events
- Lose features — if you rely on Outlook-specific features (Teams integration) or Google-specific features (Google Meet), you lose them
- Administrative limits — if your employer uses Outlook, you may not be able to switch to Google for work
- Ongoing manual work — if you add an event to the wrong calendar later, you have to move it
Best for: Starting fresh or changing jobs. Not practical if you use multiple providers for different purposes.
Comparison table
| Approach | Cost | Setup Time | Real-time | Bi-directional | Privacy Controls | Mobile Support | Best For |
|---|---|---|---|---|---|---|---|
| ICS subscription | Free | 5 min | No (12–24 hrs) | No | Limited | Fair | Quick read-only view |
| Unified app | $5–15/mo | 5 min | Yes (in app) | Yes (in app) | App-dependent | Good | Seeing all calendars in one UI |
| Hetk sync | $15–50/yr | 2 min | Yes (seconds) | Yes | Yes (full) | Yes | Real-time, multi-provider sync |
| Consolidation | Free | Hours | N/A | N/A | N/A | N/A | One-time migration |
Which approach should you use?
Quick rule:
| Situation | Best approach |
|---|---|
| Want to see the other calendar without managing sync | ICS subscription (free) |
| Want unified view but can’t change how events are stored | Unified app (Fantastical, Amie) |
| Actively use multiple calendars with real-time sync | Hetk ($15–50/year) |
| Consolidating everything into one provider | Manual consolidation (one-time) |
Specific recommendations
Google for personal, Outlook for work: Use Hetk. You get real-time sync, privacy controls to keep work events private when synced to personal, and the flexibility to edit in either calendar. $15/year.
Multiple Outlook calendars or multiple Google calendars: Use Hetk. Same real-time sync and privacy features.
Google, Outlook, and iCloud: Use Hetk for Google ↔ Outlook, and subscribe to iCloud as a read-only overlay. Best of both: real-time sync where you need it, free read-only view of your phone calendar.
Spouse or partner’s calendar: Use ICS subscription. It’s free and requires no setup. You see their events with a 12–24 hour delay, fine for planning.
Consolidating for a job change: Use manual export/import. You’re doing it once, so manual effort beats setting up a new app or service.
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 sync pairs, and the Professional plan supports up to 8 sync pairs. Both plans support unlimited calendars, so you can connect as many as needed. You can set up multiple sync pairs (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 setting them up?
Yes. Delete a sync relationship anytime in your Hetk settings. Events that were synced stay in both calendars. Hetk won’t delete them. If you want to remove the synced copies, delete them manually. Unsyncing is immediate.