Time Zone Meeting Planner
Pick a date, add your cities, and see the whole day at once: every UTC hour rendered on each city's own clock, coloured by whether it falls in work hours, the shoulder hours around them, or the middle of the night. The planner then names the hours where everyone is at work — or, when the planet says no, the compromise hours that hurt least. Shanghai, Singapore, London and New York are preloaded, because that is the combination that breaks every naive "let's meet at nine" plan.
Columns are the 24 hours of the chosen date in UTC. Each cell is that instant on the city's own clock; +1 and −1 mean the instant falls on the next or previous local day. Everything is computed with your browser's Intl time-zone data — no city list, date or result leaves your machine.
How to read the grid
Most meeting tools answer the wrong question. They convert one proposed time into other zones, which is useful only after you already know a good time exists. The scheduling problem is the search, not the conversion: with four cities spread from UTC+8 to UTC−5 there may be no hour that is polite everywhere, and a converter will happily confirm that your chosen 09:00 is 21:00 for a colleague without mentioning that 14:00 your time would have been merely early for them and mid-morning for you. A grid inverts the tool. Every hour of the day is a candidate, each city's local reality is visible at a glance, and the compromise — when compromise is all there is — is chosen with the numbers in front of you instead of discovered from the yawns on the call.
The work window is yours to set, because "work hours" are a policy, not a law of nature. A team that starts at 08:00 and a team that guards 09:00–17:00 fiercely produce different grids, and the shoulder band exists precisely for the negotiation between them: two hours either side that most people accept occasionally and nobody should accept weekly. When the planner reports a best compromise, it ranks hours first by how many cities are fully inside work hours, then by how many are at least in shoulder — a solution where three cities work and one starts early beats one where two cities work and two are up at midnight, even though both are "no overlap" to a lesser tool.
Daylight saving is the grid's moving part. Offsets are computed for the exact date you pick, using the same IANA rules your calendar uses, and the planner compares each zone's offset a week either side: a difference means a clock change is near, and any conclusion you draw for this date may be an hour wrong a fortnight later. That warning matters most for recurring meetings set during the changeover weeks, when the United States, Europe and the southern hemisphere all move on different Sundays. The companion article, finding a meeting time that respects every time zone, works through the DST traps and the overlap maths in full.
Frequently asked questions
Why is there sometimes no overlap at all?
Because the planet is round and the workday is eight hours. Shanghai and New York are twelve to thirteen hours apart, so when one is inside 09:00–17:00 the other is at night — no UTC hour puts both at work. The planner says so honestly, then shows the best-compromise hours: the ones with the most cities at work, and after that the most within work or shoulder hours, so the pain is shared deliberately instead of discovered on the call.
What do the colours mean?
Green is work hours — the window you set, 09:00–17:00 by default. Amber is shoulder: the two hours either side of the window, early starts and late finishes that most people will accept occasionally. Grey-blue is night: hours you should only ask for in an emergency, and never as a standing meeting. The grid shows each city’s own local hour for every UTC hour of the chosen date, with a +1 or −1 marker when that instant falls on the neighbouring calendar day locally.
Why does the same meeting drift by an hour twice a year?
Daylight saving time, applied on different dates in different countries — or not at all. The United States springs forward weeks before Europe, and the southern hemisphere moves in the opposite direction, so a slot that works in January can be an hour off in April. When a zone’s UTC offset changes within a week of the date you picked, the planner flags it: that is exactly when a recurring meeting silently lands an hour early or late for one side.
Can I add a city that is not in the preset list?
Yes. Below the presets there is a second list with every IANA time zone your browser knows — several hundred of them. Pick one and it joins the grid with its real offset and DST rules, straight from the same Intl data your operating system uses. Nothing is sent anywhere; the whole computation runs in your browser.
Should the recurring meeting rotate?
If no fair slot exists, yes — rotation is the honest fix. A standing meeting that is always 21:00 for the same city is a quiet tax on the same people, and they will stop coming or stop being sharp when they do. Rotate the pain monthly, or split into two alternating slots, and use the compromise hours this planner finds as the rotation points. The maths of overlap is in the companion article on finding a meeting time that respects every time zone.