Plans and limits

Five numbers limit a setup, and they run out at different times. "I'm under the calendar limit but it still won't let me" is a normal thing to hit.

What each word means

An account is one login: one Google account, one Microsoft account, one iCloud account.

A calendar is one calendar inside an account. Most people have several without realising — Google adds Birthdays and Holidays alongside your main one.

A sync is one rule connecting calendars to each other. A sync can hold more than two calendars: three client calendars pushing into one working calendar is one sync with four calendars in it, not three syncs.

That's what the numbers turn on. The sync count limits how many arrangements you have; the calendar counts limit how big each arrangement gets.

The limit that actually stops people

On Free it's the sync count, not the calendars. One sync means one rule, with a single direction and a single set of settings.

So Free handles "keep my work and personal calendars in step" without trouble. What it can't do is two unrelated arrangements at once — personal feeding into work as busy time, and a shared family calendar feeding into personal with full titles. Those are two rules.

Worth checking before you upgrade for capacity: if you're stuck at the sync limit with three or four calendars, one Push with several sources often does what you were about to build two syncs for.

The limit that isn't a number

A sync's size is weighted, not counted. A Push is charged as sources × targets, so a sync with 3 sources and 3 targets costs more than one with 5 sources and 1 target, even though it has fewer calendars.

This is why a setup can be refused while you're still under the calendar count. The message names it as a complexity limit. Fewer targets, or one-way instead of Mirror, is usually the fix.

Team has no complexity limit.

Calendars you didn't know you had

Connecting an account doesn't sync anything by itself. You pick calendars per sync, and only the ones you pick count against these limits.

Google accounts usually carry Birthdays, Holidays, and sometimes Tasks. They appear in the picker and are easy to select by accident, at which point they eat calendar slots and fill your other calendar with birthdays. Leave them unselected unless you specifically want them.

Known limitations

• Mirror allows fewer calendars per sync than Push, on both paid plans. Four against ten on Plus; five against twenty on Pro.
• The same calendar can't be in two syncs that would fight over it. You get a conflict when building the second one, which is deliberate — two syncs writing to one calendar is how duplicates happen.
• Downgrading doesn't delete anything immediately. You get a grace period to choose what to keep before the caps apply.
• Editing an existing sync doesn't re-check the caps. A sync that's already over its limit can be saved again.
• Team caps every count at 20, which is fewer total calendars than Pro's 100. Team's advantage is per-seat billing and shared administration, not raw headroom.