The method, in one breath: list each person’s city and working hours, convert every window to one reference time (UTC), then find where they intersect. The overlap starts at the latest start and ends at the earliest end. Pick a time near the middle of that window and convert it back to each person’s clock.
Two cities are easy. Three or more, on different continents, is where intuition breaks down: the shared part of the working day can collapse to a single hour, or disappear entirely. This is now the norm rather than the exception: Buffer’s 2023 State of Remote Work found that 62% of remote workers have immediate teammates spread across multiple time zones. The fix is not cleverness, it is a tidy four-step process you can run every time.
Step 1: List each member’s city and working hours
Start with the raw facts. For every person, write down the city they actually work from and the hours they consider workable. Use the city, not the country, because a country can span several offsets. “9 to 5” is a fine default, but ask: some people guard their mornings, others finish at 4.
- Person and city — e.g. “Maya, San Francisco”.
- Local working hours — e.g. 9:00 AM to 5:00 PM.
- Hard limits — school runs, no early calls, and so on.
Step 2: Convert every window to one reference time
The trap is comparing local clocks directly. Don’t. Translate each person’s hours into a single reference so the numbers are finally comparable. UTC is the natural choice: it never shifts and every offset is defined against it. To convert, subtract the city’s offset from local time (a UTC+1 city at 09:00 is 08:00 UTC).
Step 3: Find where the windows intersect
With every window in UTC, the overlap is simple arithmetic. The shared window starts at the latest of all the start times and ends at the earliest of all the end times. If that latest start falls after the earliest end, the windows don’t touch and there is no common hour during normal working time.
A worked example: San Francisco, London, Singapore
Take a team of three, each working 9:00 AM to 5:00 PM local. In June, San Francisco is UTC−7, London is UTC+1, and Singapore is UTC+8. Convert each working day to UTC:
| Person & city | Local hours | Offset | In UTC |
|---|---|---|---|
| Maya · San Francisco | 09:00–17:00 | UTC−7 | 16:00–24:00 |
| Olu · London | 09:00–17:00 | UTC+1 | 08:00–16:00 |
| Wei · Singapore | 09:00–17:00 | UTC+8 | 01:00–09:00 |
The latest start is Maya’s 16:00 UTC. The earliest end is Wei’s 09:00 UTC. Since 16:00 is after 09:00, the three working days never intersect. This is the usual outcome for a true Americas–Europe–Asia spread: by the time the US west coast wakes up, Asia has long since logged off.
Drop Singapore and the picture changes. San Francisco (16:00–24:00 UTC) and London (08:00–16:00 UTC) just touch at 16:00 UTC — that is 9:00 AM in San Francisco and 5:00 PM in London. A single shared minute, right at the edge of both days. Stretch either person’s hours by thirty minutes and you get a usable slot.
Step 4: Pick the middle, not the edge
When you do have a window, resist booking its first or last minute. A time at the edge lands at the very start or end of someone’s day, where commutes, school runs and focus blocks live. Aim for the centre of the overlap so everyone has buffer on both sides. The middle is the kindest, most reliable choice.
Offsets are not fixed. When a region changes its clocks, its UTC offset shifts by an hour, and countries don’t all change on the same date. A window that works in February can move or vanish in July, so recheck whenever clocks change.
When there is genuinely no overlap
For the widest teams, honesty beats heroics. If no shared hour exists, choose one of these instead of forcing a 6:00 AM call on someone forever:
- Rotate the pain. Move the meeting time week to week so the same person is not always the one calling in at dawn or midnight.
- Flex occasionally. Ask one person to shift their hours for a specific meeting, with plenty of notice, rather than as a standing expectation.
- Go asynchronous. Replace the standing call with written updates and reserve live time for the moments that truly need everyone in the room.
Let the app do the arithmetic
Running this by hand is fine once. Doing it every week, with daylight saving shifting offsets underneath you, is where mistakes creep in. Atlas pins each person on a world map, shades everyone’s working hours, and shows the overlap as a single highlighted band — then writes the chosen time to your calendar in one tap. For the manual version end to end, see how to schedule a meeting across time zones.
Frequently asked
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