Meeting Planner: Find the Best Time Across Time Zones

Scheduling a meeting across participants in several countries sounds simple in theory — just pick a time — and often turns out frustrating in practice: a time that suits Paris falls in the middle of the night in Tokyo, an ambiguous "9 am" becomes a source of missed calls, and daylight saving time occasionally shifts everything by an hour without warning. This planner computes, exhaustively, every participant's local time for every possible slot across a two-day window, and highlights the ones that genuinely work for everyone.

Why time zones complicate scheduling

A time zone isn't just a simple whole-hour offset. Most countries do use a whole number of hours relative to Coordinated Universal Time (UTC), but several notable exceptions exist: India and Sri Lanka sit at UTC+5:30, Nepal at UTC+5:45, some Australian territories at UTC+9:30, and New Zealand's Chatham Islands at UTC+12:45 (UTC+13:45 in southern-hemisphere summer). A manual "back of the envelope" conversion easily drops these half-hours and quarter-hours, which is enough to shift an appointment by a full time slot.

The second, more insidious trap is the date boundary. As soon as the gap between two time zones exceeds a few hours, a meeting scheduled on a given day in one zone can land on the previous or following day in another. Announcing "Tuesday 2 pm Paris time" without noting that this corresponds to "Wednesday 9 pm" in Tokyo is a classic source of confusion, especially for participants who don't actively check a time zone converter before every meeting.

A third, lesser-known trap concerns time zones whose rules change over time rather than simply shifting with the seasons: a country can decide to drop daylight saving time, join a neighboring zone, or change its reference offset by political decision, sometimes with only a few months' notice. The IANA database, updated several times a year, absorbs these changes — one more reason never to hard-code your own offset table in a spreadsheet or document, which sooner or later silently goes stale.

Working hours: conventions vary by region

The "9 am-6 pm" range isn't universal. The working week itself differs: it runs Sunday through Thursday in several Gulf and Middle Eastern countries, with Friday and Saturday as rest days, while it runs Monday through Friday across most of Europe, the Americas, and East Asia. Office hours themselves vary too: a day starting around 8 am and ending early in Northern Europe, a long lunch break pushing hours later into the afternoon in some Mediterranean or Latin American countries, and hours stretching well into the evening in parts of Asia.

That's why this planner never assumes a single working range for everyone: each participant has their own working hours, individually adjustable, which determine what counts as "within office hours" for them. This also lets you represent more specific cases — shift work, staggered schedules, part-time — without forcing everyone into the same mold.

Daylight saving time (DST): the classic trap

A good part of North America and Europe moves its clocks forward or back twice a year, but not on the same dates: the European Union switches at the end of March and the end of October, while the United States and Canada switch roughly two to three weeks earlier in spring and later in autumn. During those few mismatched weeks, a gap that's normally, say, 6 hours between two cities can temporarily become 5 hours, or vice versa.

And the southern half of the planet applies daylight saving time in reverse: Australia and parts of Chile or Paraguay spring forward while the northern hemisphere falls back, and vice versa. Many countries simply don't observe daylight saving time at all (most of Africa, most of Asia, Iceland, parts of South America), which means the gap with a zone that does change twice a year is never fully fixed across the whole year.

This planner solves the problem at the root: every slot in the grid corresponds to a precise UTC instant, converted into each time zone on the exact chosen date. Whatever daylight saving rule is (or isn't) in force that day in each zone is therefore automatically accounted for, with no rule for you to remember.

How to read this planner's grid

The grid shows one column per slot (every 15, 30, or 60 minutes depending on the chosen granularity) and one row per participant, over a window of 24 to 72 hours. Each cell is colored according to a four-level verdict: optimal when the slot falls within the working hours of every participant, acceptable when it falls outside those hours but stays within a reasonable range (7 am to 10 pm) for everyone, difficult when it falls in the dead of night for exactly one person, and avoid when it falls in the dead of night for several people at once. The three best slots in the window are automatically highlighted, but nothing stops you from dragging the selection elsewhere in the grid to explore other options — every move updates each participant's local time live.

Best practices for announcing an international meeting

Always state the time with the time zone made explicit — never on its own ("2 pm UTC" or "2 pm Paris time", never a bare "2 pm" that assumes everyone shares your time zone). Add, for each participant or region represented, the corresponding local time rather than asking everyone to work it out themselves. Note the local date whenever a day boundary is possible, with an explicit note like "Wednesday your time". Finally, always attach a calendar invite (.ics) rather than plain text: each participant's calendar app then automatically shows the correct time in their own time zone, with no risk of manual conversion error.

Common mistakes to avoid

Relying on a "remembered" gap rather than a calculation for the exact date. A time zone gap held in memory ("that's 6 hours ahead") can become wrong during the weeks when only one of the two countries has switched to daylight saving or standard time.

Forgetting that a weekday in one time zone can be a weekend in another. Rest days don't fall on Saturday and Sunday everywhere; checking this avoids proposing a slot that lands, for some participants, on a day off.

Ignoring non-integer offsets. Rounding +5:30 or +5:45 to the nearest quarter or full hour introduces a systematic error that can shift the meeting by a whole slot for the participants affected.

Fixing a single time without ever checking everyone's actual working hours. A slot that looks "acceptable" (outside the dead of night) can still fall well outside a participant's usual office hours, which carries a real cost once the meeting repeats every week.