How to keep two work calendars from seeing each other’s details

Two employers, or a job plus a side business, usually means two calendars that know nothing about each other — until someone books a 9am on one and you already have a 9am on the other. The instinct is to copy events across so each calendar has the full picture, but a full copy also copies the reason: the meeting title, the attendees, who you're working with and on what, sitting on a calendar that belongs to a completely different employer or client. What you actually need is much smaller than a full copy: each calendar only needs to know that a slot is taken, not what it's taken by. A busy-only mirror does exactly that, automatically, and there is also a manual version if you'd rather not connect anything.

Why copying full events defeats the purpose

Forwarding invites or duplicating events between the two calendars is the obvious first move, and it's also the one that leaks the most. A meeting titled with a client's name, or an internal project codename, or just “side business — call with X,” landing on your employer's calendar tells them exactly what you're doing with the time you're not working for them. Attendee lists are worse — an email address on an invite identifies a person, sometimes a competitor, sometimes a client the other side has an actual policy against. None of that needs to be visible for the calendars to do their one real job, which is stopping you from being double-booked.

The point of keeping two work calendars separate isn't secrecy for its own sake — it's that neither employer or client is entitled to see the other's business just because you happen to be the person in both. The time itself is the only thing that needs to cross the boundary.

The busy-only mirror: what crosses, what never does

A busy-only mirror copies a plain “Busy” block — no title, no description, no attendees — from one calendar to the other whenever an event is created. Calendar A shows a meeting with real details, visible only to you and whoever you already shared it with; Calendar B shows the same window as “Busy,” nothing more. Run it in both directions and each calendar always reflects the other's time commitments without ever learning what they're for.

What crosses: start time, end time, and the fact that the slot is taken. What never crosses: the title, the description, who's on the invite, or which employer or client the original event belongs to. The source event itself is never touched or modified — the mirror only ever reads it and writes a separate busy block on the other calendar.

Reschedules, deletes, and no loops

The reason a manual version of this is hard to keep up is that events move. Reschedule the source meeting and the busy block that was copied from it needs to move too, or the other calendar quietly goes stale — showing you free when you're not, or busy when you're not, until someone notices. Delete the source and the copy needs to go with it. A working mirror follows both: the copy tracks the source through reschedules and disappears when the source does.

The other failure mode worth naming is the mirror copying its own copy back to where it came from — a “Busy” block on Calendar B triggering a new block on Calendar A, which the mirror then reads as a new event and copies back to B, and so on. A mirror worth using tags every copy it creates so it recognises its own work and never re-mirrors it, which is the difference between two calendars staying in sync and two calendars slowly filling up with duplicate busy blocks.

Offering time without showing which calendar is busy

Mirroring solves the two calendars not double-booking each other. It doesn't, by itself, solve how you offer time to someone outside either one — a new client, a recruiter, anyone who needs to book you. If you send a booking link that only reads one of the two calendars, it can offer a slot that's actually taken on the other, which is the same double-booking problem in a different shape.

The fix is a link built from both calendars merged together, so the times it offers are genuinely free on either side — and the person booking never sees that there even are two calendars, let alone which one has you busy at a given hour. BusyBoard is the automated way to run both halves of this: it mirrors busy-only blocks between your calendars so each one reflects the other without either seeing the other's details, and it gives you one link with your real merged availability, with any booking on it landing for your approval before it touches a calendar.

What's free and what isn't

The share link itself is free to use, with one connected calendar, a two-week availability window, and syncing every ten minutes. Mirroring busy-only blocks between two calendars — the part that keeps both sides accurate without you doing it by hand — is a Pro feature, with a 14-day free trial and no card required to start it. If you'd rather not connect a second calendar to your account at all yet, the manual busy-block copy described above still works; it just asks more of you every time something changes.

For the client-facing version of this same problem — sharing merged availability with someone at another company entirely — see finding a meeting time across two companies.