The short version
- New York, London and Sydney have no shared slot inside normal office hours, so someone always takes the early or late turn
- Offer two or three options written in the other person’s local time, zone named, and rotate who takes the painful slot
- Daylight saving switches on different dates in the UK, US and Australia, so always check the offset for the meeting date, not today
- Every global call still needs a physical room at each end, booked in that office’s own time
Assistants who schedule internationally will tell you the hardest part is not the arithmetic. It is holding three cities’ working days in your head at once while making everyone feel considered rather than converted. One veteran put it simply: awake is not the same as available.
The overlap maths, honestly
Start with the uncomfortable truth. Take generous office hours of 8am to 6pm in each city. During the northern winter, New York sits five hours behind London and Sydney sits eleven ahead. For all three to be inside office hours, London would need a slot that is after 1pm for New York’s sake and before 7am for Sydney’s. That window does not exist. There is no fair time, only a choice about who takes the hit.
The practical answer most global teams settle on is rotation. One month the call runs at 8pm London, which is 3pm in New York and 7am the next morning in Sydney. The next month it moves so a different city takes the edge-of-day slot. The maths never improves. The fairness does.
The two rules that prevent most mistakes
First, always write times in the other person’s local time, with the zone named. “Would Tuesday at 4pm London time (11am New York) suit?” gives the recipient a yes-or-no rather than a puzzle, and it proves you did the conversion so they do not have to.
Second, never trust today’s offset. The UK, the US and Australia all change their clocks on different dates, and the southern hemisphere moves in the opposite direction. For a few weeks each spring and autumn the usual gaps are wrong, and that is exactly when a 3pm call quietly becomes a 2pm one. Check the offset for the actual meeting date, every time.
A working reference for the common cities
| City pairing | Typical gap | Watch out for |
|---|
| New York and London | 5 hours | Drops to 4 hours for a fortnight in March when the US changes first |
| London and Sydney | 9 to 11 hours | Both ends shift, in opposite directions, in spring and autumn |
| New York and Sydney | 14 to 16 hours | Usually a different calendar day, so name the date as well as the time |
The half-hour zones deserve their own warning. India runs on a half-hour offset and parts of Australia do too, so a mental calculation that rounds to whole hours will land you thirty minutes out, which is worse than being an hour out because nobody suspects it.
The room at each end
A global call is not just a calendar event. The London end needs a video-equipped room in London, the Sydney end needs one in Sydney, and each has to be booked in that office’s local time by someone who may have never set foot there. This is where booking on behalf earns its keep: you reserve the room in the other office through the room booking system, the hold lands on the local calendar correctly through the calendar integration, and you never have to work out what 8pm London is on a wall clock in Sydney because the system already knows.
An interactive floor plan helps with the part you cannot see: which of the Sydney rooms actually has the video kit and seats eight. And because early-morning slots are precisely the ones people forget to cancel, auto-release makes sure a 7am room that nobody claims goes back into the pool instead of sitting empty while the call happens from a laptop in the kitchen.
A closing checklist
Before the invitation goes out: offset checked for the meeting date, times written in each recipient’s local zone, the painful slot rotated, a room booked at each end in local time, and the invitation set so every calendar renders it correctly. Five checks, thirty seconds, and the call starts with everyone in the right place at the right hour. For more on how assistants run this day to day, see how teams use HybridHero on our executive assistants page.