TIME ZONES
Meeting across time zones: find a slot that works everywhere
When people are 8–15 hours apart, the realistic overlap is often only 2–4 hours a day. Find the window, then pick a fair point inside it, then write the invite. Do not subtract a memorised offset in your head.
Quick answers
Is there any overlap across 12 time zones?
Yes, but it is often a thin morning-versus-late-evening strip. A 30–45 minute call, or an async note, is more realistic than a forced hour. Check that date in the tool; do not assume anything past midnight is impossible.
Why did last week’s time move by an hour?
Usually daylight saving. One side changed, or they changed on different weekends, and the window shifted. Recalculate with the date in that week.
Can the invite just say 09:00?
Not unless everyone stays in one zone forever. Write the city’s local time plus a zone name or UTC offset, and store the correct IANA zone on the calendar event.
Why is India always off by 30 minutes?
India Standard Time is UTC+5:30, not a whole hour. A mental “12 hours apart” misses by 30 minutes. Nepal is UTC+5:45. Use the database; do not round.
01You want overlap, not a full working day for everyone#
When attendees sit 8–15 hours apart, one person’s morning is often the other’s late night. There is no full day of “everyone’s office hours” — only a short window when people are both awake and able to talk. Afternoon in one region against morning in another is the usual shape.
Lock the window first, then pick a time inside it. A two-hour window forced into a four-hour workshop makes the same side stay up every week. Each extra timezone cuts the edges you thought were fine.
02How to find the overlap#
Convert one instant into every attendee’s local clock, or draw a 24-hour row per zone and look for the shared working hours. A practical start: convert your morning into their late afternoon, then slide by whole hours and recompute every zone each time.
The table is a planning sketch, not that week’s calendar. Daylight saving moves London, New York and much of Europe by an hour; Shanghai, Singapore and Hong Kong usually do not. A slot that works in May can shift as a block by November.
| Pair | Approx. winter gap | A common overlap | Spell out in the invite |
|---|---|---|---|
| Shanghai ↔ London | 8 hours | 16:00–18:00 Shanghai ≈ 08:00–10:00 London | Whether the UK is on summer time |
| New York ↔ London | 5 hours (winter) | 09:00–12:00 New York ≈ 14:00–17:00 London | US and UK DST weekends differ |
| New York ↔ Shanghai | 13 hours | 08:00 New York ≈ 21:00 Shanghai | Who takes the evening, and whether you rotate |
| India ↔ US West | 12.5–13.5 hours | 09:00 Bengaluru ≈ 19:30 or 20:30 the previous evening in California | UTC+5:30 — do not round to whole hours |
03Three scheduling examples#
Example 1: a 09:00 Shanghai meeting that must include London. In winter that is 01:00 in London — outside the overlap. Move it to 16:00 Shanghai (08:00 London in winter, 09:00 in summer) and both sides can attend. Example 2: a weekly New York–London call. In July, 10:00 in New York is 15:00 in London (BST); in January, 10:00 in New York is still 15:00 in London (both on standard time). It looks unchanged because both sides shifted. In the weeks when the switch weekends do not line up, the gap is 4 hours not 5: that same 10:00 ET is 14:00 in London, not the 15:00 you memorised. The US switches first in spring; the UK switches first in autumn; both mismatch weeks are 14:00.
Example 3: 09:30 in Bengaluru and San Francisco. India is UTC+5:30. Subtracting a round 12 hours misses by 30 minutes and parks the other person on the wrong side of 20:00 versus 21:00. Pick a real date in the tool; do not do it in your head. Across the date line, the invite must name the calendar day: your Tuesday can be their Monday.
04Daylight saving can move the window mid-week#
DST starts and ends on different dates, and some regions never change. An overlap that works in May can sit an hour later in November. The jump can land on a Wednesday: North America and Europe often switch on different weekends.
A calendar event that says only “every Tuesday 09:00” with no zone expands in each recipient’s system timezone. The DST week, someone arrives an hour early or late. Store an IANA zone on the event (America/New_York) or write “09:00 New York / 14:00 London BST” in the body.
05Half-hour and 45-minute zones#
India is UTC+5:30, Nepal UTC+5:45, and some Australian areas have used :30. A habit of whole-hour offsets parks the meeting in the other person’s night or just outside the overlap. Iran and others also use half hours; do not assume “Asia is whole hours”.
The planner reads that day’s offset from IANA, including these fractions. NIST and similar labs keep the time scale; civil zone boundaries and DST still come from IANA. You are checking “this city on this date”, not “this country is always +8”.
06Pick a time that does not always punish the same side#
The least-bad slot is usually near the middle of the overlap, not your favourite round hour. Recurring meetings can rotate the window once a quarter so the same people are not always on 06:30 or 22:00. With a small group, asking the side with the smaller gap to give 30 minutes beats asking the far side to stay up every week.
A recording does not replace a meeting that must decide live, but it lets people outside the window catch up. Before you send, paste the candidate into this site’s timezone planner and click every city that will actually join.
07Common mistakes#
Subtracting a frozen “London is eight hours behind”; ignoring DST; assuming every zone moves in whole hours; putting only one city’s clock on the invite; treating a flight’s local arrival as the departure city’s clock. Naming “Tuesday” without a date across the date line.
Another is using the phone’s system zone instead of the meeting location — the device already switched to Tokyo on a trip, while the invite still expands as Shanghai. Read every city the tool lists, not the lock screen.
08Checklist before you send the invite#
Confirm which calendar day the instant falls on for each person; check DST that week; write local time plus offset or an IANA name; open half-hour zones on their own row. Then paste the moment into the timezone planner and send.
This page is how to schedule, not how to recover from jet lag. The jet-lag guide covers sleep and light after you land. The planner follows IANA; if a region changes its offset at short notice, results lag. For a high-stakes slot, get a spoken confirmation.
Sources
MORE GUIDES
Keep reading before you go
Jet lag: adjust to the new timezone before you land
Jet lag is the body clock still running on the departure city while the destination is already on another day-night cycle. It is most obvious after three or more zones. Direction, light and the first two days matter more than sleeping the entire flight. This page is not treatment.
Connecting flights: how to verify transit visas, bags and self-transfers
A short layover is not automatically visa-free. Your passport, airport route, ticket structure and baggage process can each change the answer.
Check these before travelling with an eSIM.
Do not wait until arrival to discover an incompatible phone, an expired QR code or the wrong data line. Installing and activating are two steps: install while you have internet, turn data on after you land.