Time zone meeting planner

1. Add every participant's zone. Your own time zone is detected and added automatically. Search by city — Tokyo, Berlin, Denver — and pick from the suggestions; up to eight zones fit on the board at once.
2. Pick the meeting date. The planner defaults to today, but the date matters more than people expect: time zone differences shift around daylight saving changes, so the right slot for next week is not always the right slot for November.
3. Scan for green. Each row shows that zone's local clock across the same 24 hours. Look for columns where every row is green (9:00–17:00) — or, failing that, where the amber compromise lands on the people who agreed to take it.
4. Click the column and share. Selecting a column shows the exact local time, weekday, and any day rollover for every zone. Copy times produces a tidy text block for email or Slack, and Copy link shares this exact view — zones, date, and selected slot included.

The grid uses three shades per zone, based on that zone's local hour. Green marks 9:00 to 17:00 — conventional business hours, when a meeting inconveniences nobody. Amber marks the shoulders: 7:00 to 9:00 in the morning and 17:00 to 21:00 in the evening, times most people can do occasionally but nobody should be assigned permanently. Grey is the rest — night. A slot where any row is grey is not a meeting time; it is a favor someone is doing you at 3 a.m.

The half-hour resolution is deliberate. Plenty of real overlap windows are only 30 or 90 minutes wide — London and Sydney, for example — and whole-hour grids round those windows away. Half-hour columns also make zones with :30 and :45 offsets (India, Nepal, parts of Australia) line up honestly instead of being fudged to the nearest hour.

Most time zone mistakes are not about the base offset — they happen in the weeks around daylight saving transitions, when half the world has shifted and the other half has not. New York and London are usually 5 hours apart, but for a couple of weeks each spring the gap is 4 hours because the US changes clocks earlier than Europe. A meeting planned by memory ("London is always 5 ahead") lands an hour off exactly then.

This planner sidesteps the whole class of bugs by never doing offset arithmetic. Every half-hour column is a precise instant in time, and each zone's label for that instant comes from your browser's built-in IANA time zone database — the same rules your operating system uses to set your clock. If the date you pick crosses a DST boundary in one zone but not another, the grid simply shows the true local times, including the odd 23- or 25-hour day. That is also why picking the actual meeting date, not just "some Tuesday," is worth the extra click.

Deciding on a time is half the job; communicating it without ambiguity is the other half. Copy times writes each zone's weekday, date, local time, and time zone abbreviation on its own line — paste it into the meeting invite, a Slack thread, or an email, and every recipient can find their own city instead of doing arithmetic from yours. It reads like "New York: Tue, Jul 21 · 09:00 EDT", which leaves no room for the classic "wait, whose 9 a.m.?" reply.

Copy link goes further: the zones, date, and selected slot are encoded in the URL itself, so a teammate opening your link sees exactly the board you built and can counter-propose by clicking a different column and sending the link back. No account, no saved documents — the URL is the document.

Every pairing has its own rhythm, and it shifts with DST — but knowing the usual shape helps you aim before you even open the grid:

Treat these as starting points, not answers — the grid computes the real numbers for your specific date, which is what actually goes on the invite.

• Rotate the pain. When no all-green column exists, alternate who takes the amber slot meeting to meeting — a recurring call that is always 21:00 for the same office quietly burns that office out.
• Watch the day boundary. The +1 day badge matters: your Thursday afternoon is Sydney's Friday morning, and "end of week" means different calendar days to each side.
• Say the zone, every time. Always write times with their zone — the Copy times block does this for you — and prefer each person's local time over "my time" conversions.
• Respect lunch and school runs. Green means working hours, not availability; 12:30 local or the 8:00 school drop-off can be worse than 17:30 for a given person. Ask.
• Default to async when the window is tiny. If the only overlap is one amber half hour, a recorded update or a document with comments often beats forcing a live call.

Roughly a billion people live in zones that are not a whole number of hours from UTC. India runs at +5:30, Nepal at +5:45, central Australia at +9:30, Newfoundland at −3:30. Tools that model the world as whole-hour offsets either exclude these zones or silently round them, which is how a "10:00" invite turns into a 10:30 surprise in Mumbai. Because this planner works in half-hour columns and formats every instant with the real zone rules, Mumbai's 9:00 sits visibly between whole hours of UTC, exactly where it belongs — and Kathmandu's :45 offset appears in the summary card and copied text with the correct minutes, even where the compact grid labels round to the nearest cell.

Booking tools like Calendly and the scheduling assistants inside Google Calendar and Outlook solve a different problem than this planner does. They answer "which of my free slots should someone pick?" — which requires connecting your calendar, sharing availability, and often a paid seat per host. A world clock planner answers the question that comes before that one: "what time of day is even humane for this particular mix of cities?" That is a conversation you have while composing an email to a client in another hemisphere, proposing options to a candidate, or setting a recurring team call — moments when you want the answer in seconds, with nothing connected and nobody notified.

In practice the two work in sequence: use this grid to find the two or three columns that are green for everyone, then offer those times through whatever booking flow you normally use. The copied time block drops straight into the invite body, so each recipient sees their own local time without clicking anything.

The header row across the top of the grid shows UTC — Coordinated Universal Time — and every column is one half-hour step of it. That is not a developer affectation; it is what makes the whole board trustworthy. UTC never observes daylight saving, never skips an hour, and never repeats one, so it is the one clock every zone can be measured against on any date. Each cell in a row is simply that zone's local answer to the question "what time is it when UTC reads X?" — which is also why rows for India or Newfoundland shift half a cell relative to whole-hour zones instead of pretending to align.

A useful side effect: engineers, pilots, and ops teams who already coordinate in UTC can read the ruler directly, and the selected instant in a shared link is stored as an exact UTC timestamp — so the link means the same moment to everyone who opens it, no matter where they are.

Who you meet with, and when, is calendar data — some of the most sensitive metadata a company produces. This planner does not want it. The zone list, the grid, the conversions, and the shareable link are all computed by JavaScript in your browser tab using the time zone database your browser already ships. No account, no cookies for the tool itself, no meeting details sent to a server: the shared link carries the state in plain sight in the URL, readable by you, and the page works offline once loaded. Compare that with calendar-connected schedulers, which necessarily read your availability to function — the right tool when you need booking pages, but overkill when you just need to find Tuesday's slot.

• Remote and distributed teams finding a standup or all-hands slot that respects engineering in Warsaw, sales in New York, and support in Manila.
• Freelancers and agencies proposing call times to clients abroad without the back-and-forth of "does 3 p.m. work? — whose 3 p.m.?"
• Recruiters and candidates scheduling interviews across continents where a day-boundary mistake means a no-show.
• Event and webinar hosts choosing a start time that lands tolerably across every region they are inviting.
• Families and friends spread across countries, picking a call time that is after dinner for one side and before work for the other.

If your scheduling work involves raw Unix timestamps rather than cities, the timestamp converter is the companion tool, and the cron expression generator handles the recurring-schedule side of the same problem.