Meeting Time Zone Planner
Find meeting times that work across multiple time zones at a glance, with working hours shaded so unreasonable slots are obvious before you propose them.
Green = comfortable working hours (8 AM–6 PM). Columns follow your local time today.
The third zone is the one that breaks it
Taking the 19 cities on this page and asking whether an ordinary working day — 8 in the morning to 6 in the evening, local — has any hour in common:
| Combinations | Share a working hour | |
|---|---|---|
| 171 pairs | 138 | 81% |
| 969 triples | 459 | 47% |
Adding one more city to a call that already works nearly halves the chance of it still working. Which matches the experience of arranging one: two offices is a scheduling problem and three is a negotiation.
| Team | Hours in common |
|---|---|
| New York + London | 5 |
| London + Mumbai | 5 |
| New York + London + Berlin | 4 |
| Los Angeles + Tokyo | 3 |
| Los Angeles + London | 2 |
| New York + London + Tokyo | none |
The famous case is the worst one. New York, London and Tokyo — the three financial centres, the standard example of a follow-the-sun team — have no hour of the working day in common at all. Any two of them do.
And the rule turns out to be exact
33 of the 171 pairs have no common working hour, and no single awkward city is responsible. Auckland appears in 6 of them, the most of any city and still under a fifth — every one of the 19 is stranded against somebody.
Checked against every pair, the rule is not approximate: two cities overlap if and only if they are less than 10 hours apart, and when they are, the overlap is 10 hours minus the gap. So 9 hours apart gives you exactly one hour, and 10 gives you none.
Los Angeles cannot reach Mumbai, London cannot reach Sydney, and São Paulo cannot reach Tokyo, all for the same reason and by the same arithmetic. The half of a call that has to move is the one with less to lose, which is why these meetings end up at seven in the morning on one side rather than in the middle for both. There is no middle.
One caveat worth stating: all of that is measured on a January instant. Six months later many of these offsets have moved by an hour, in different directions, while 8 of the 19 do not observe daylight saving at all and have not moved while everything around them did. The shape of the answer is stable; the exact count is not — which is how a standing meeting quietly breaks twice a year.
How to use
- Add each participant's city or time zone.
- Scan the grid for hours that suit everyone.
- Note who is being asked to take an unsociable slot.
- Confirm the date, since a slot may fall on different days.
Frequently asked questions
Why do meeting times drift a few weeks a year?
Because daylight saving changes on different dates in different countries. Between mid-March and late March, and again in late October and early November, the usual gap between US and European cities shifts by an hour. A recurring meeting set once will move for one side.
How wide a spread can one meeting cover?
Comfortably about eight hours of difference before somebody is being asked to work outside reasonable hours. Beyond that, no time suits everyone, and the fair approach is rotating which region takes the awkward slot rather than always defaulting to headquarters.
What is the fairest way to schedule across many zones?
Rotate the inconvenience, and record decisions in writing for anyone who cannot attend. Teams spread across more than about twelve hours of difference generally work better by reducing the number of synchronous meetings than by finding cleverer times for them.
Should I send invitations in a specific time zone?
Send a proper calendar invitation with the zone attached rather than a time written in a message. Calendar software converts correctly for each recipient; a time typed in an email gets misread, particularly by anyone who forgets which zone the sender is in.
Do all zones shift by whole hours?
No — India is at 5 hours 30 minutes and Nepal at 5 hours 45, among others. A grid assuming whole hours will misplace those participants, which is a small error with a large effect on whether someone joins on time.
Does the southern hemisphere complicate things?
Considerably. Australia and parts of South America shift their clocks in the opposite season, so the gap to Europe or North America changes twice a year in both directions. A meeting comfortable in June may be unreasonable in December.
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