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Calendar sync guide

One-Way vs Two-Way Calendar Sync

One-way calendar sync copies events from a source calendar to a target calendar, while two-way sync keeps both calendars aligned when either side changes.

Updated

Quick answer

Use one-way sync when one calendar is the source of truth. Use two-way sync when changes on either Google Calendar or Outlook should be reflected on the other side.

Best for

  • One-way sync: blocking work time on a personal calendar or personal time on a work calendar.
  • Two-way sync: keeping two actively used calendars aligned.
  • Keyword-filtered sync: copying only selected events between calendars.

Not best for

  • One-way sync is not ideal when both calendars are edited often.
  • Two-way sync may be more than you need if one calendar only needs busy blocks.
  • Any sync setup should be reviewed before connecting calendars with sensitive event titles.

What is one-way calendar sync?

One-way sync treats one calendar as the source and another calendar as the destination. It is useful when you want events from Calendar A to block time on Calendar B without Calendar B changing Calendar A.

What is two-way calendar sync?

Two-way sync watches both connected calendars. When either calendar changes, the paired calendar can be updated too. This is helpful when both calendars are active parts of your workflow.

How does Calendar FreeSync handle sync direction?

Calendar FreeSync supports one-way and two-way sync, so users can decide whether one calendar is the source of truth or both calendars should remain continuously aligned.

Common questions

Which sync direction is safer for privacy?+

One-way busy/free blocking is often simpler for privacy because it can protect availability without requiring every calendar to become a full copy of the other.

Can Calendar FreeSync run two-way sync?+

Yes. Calendar FreeSync supports one-way and two-way sync between supported Google and Microsoft calendars.

Need simple Google and Outlook sync?

Calendar FreeSync keeps availability aligned without replacing the calendars you already use.

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