Timezone Meeting Planner — One Instant, Every Attendee's Clock, and the Hours That Actually Work
Type a date and a clock reading, say which zone that reading belongs to, then pick up to six cities. Each one gets its local time, weekday, UTC offset, whether the day rolls over, and whether that hour falls inside your working window. Nudge the instant by an hour and a 24-hour scan lists every slot ranked by how many people would be at work. Clocks that skip or repeat an hour around a daylight-saving change are reported as they are, and nothing you type leaves this device.
| City | Local time | Weekday | Offset | vs you | Status |
|---|
Every hour from this one onward
| Shift | UTC | Clocks | At work |
|---|
Text summary
Wall-clock faces and UTC offsets
One instant, read on several clock faces
One instant, seen from several clocks at once. Type a date and a clock reading, say which zone that reading belongs to — that last step is where most planning mistakes happen, because a bare “21:00” means three different meetings depending on who wrote it. Every city you then pick gets its own local time, weekday, UTC offset, a +1 day / -1 day marker, and a verdict against the working window you set.
The 34 buttons are ordered west to east, so a row of picks reads like a map. Anything the browser’s time-zone database knows can be typed in by its IANA name (America/Nuuk, Asia/Urumqi, Europe/Zaporizhzhia), which matters because the short names people use are usually wrong. Six places is the most this table stays readable at.
The two numbers worth reading
Spread is the distance from the earliest clock to the latest one, and it includes your own zone — with Kathmandu and Darwin picked while you sit at UTC, it reports 9 h 30 m, not the gap between the two cities. Half-hour and 45-minute offsets are kept as minutes, never rounded into hours, so +05:45 and +12:45 stay visible as what they are.
Best shift comes from the 24-hour scan under the table: every hour starting from your instant, ranked by how many of the picks would be inside the working window at that moment. Hours that tie are labelled as ties rather than smoothed over, and the scan is honest about the empty case — a Saturday says “no shift in the next 24 hours puts a single place inside the window”, because that needs an agreement, not a cleverer window.
Wall-clock readings that are not one instant
Near a daylight-saving change a clock can skip an hour or repeat one, and both cases are reported instead of quietly picking an answer:
- New York, 2026-03-08 at 02:30 — the spring-forward jumps from 01:59 to 03:00, so that reading never occurs. The plan anchors to 03:30 and the note says so.
- New York, 2026-11-01 at 01:30 — the autumn fallback makes that reading happen twice, at 05:30Z and 06:30Z. The plan anchors to the first and the note names the second.
- A city whose clocks change within the next 24 hours of your meeting is flagged, because the scan across those hours is not uniform.
The zone database here is the browser’s own (ICU), so offsets come from the same source that renders your system clock.
What it deliberately does not do
It does not know holidays, company-wide closures, or a “working window” that differs per person; the window is the same local range for every city you pick. It will not pick a time for you — it ranks hours by how many people are at work, and the judgement about whose hour gets inconvenienced stays yours. And it never asks a service to fill anything in: no lookup, no submit, no call carries your choices out of the tab. The date, the reading, and the cities you choose never leave this device, and the calculations run offline, opened straight from disk.