Why time zone math is harder than it looks
Cross-zone scheduling looks like a tiny problem until you actually try to do it well. Daylight saving transitions don't line up — the US shifts on a different weekend than Europe, and most of Asia doesn't shift at all. Half-hour and 45-minute zones (India, Nepal, parts of Australia) trip up almost every mental shortcut. And the moment you have more than three people, the search space for "a time that works for everyone" grows fast.
Doing it in your head leads to the classic mistake: you confidently propose 4 PM your time and discover later that 4 PM in Berlin is 7 AM in San Francisco, which nobody wants. The grid above runs the math for you so you can spot overlap windows visually instead of converting times one by one.
How to read the grid
Each row is one participant. Each column is one hour of the day, labeled in the first participant's local time (the anchor). The number in each cell is the local time at that hour for that row.
The color tells you whether a meeting at that hour would land in everyone's working hours:
- Green — every participant is in their working hours. This is what you're looking for.
- Yellow — some participants are in working hours, but not all. Sometimes worth it; usually means somebody has an early or late call.
- Gray — nobody (or almost nobody) is at work. Don't schedule here unless you have to.
Tips for global teams
Aim for the edges of the working window
If your golden window is short, schedule at the start or end rather than the middle. Someone in Asia who has the meeting at 8 AM their time can still have a productive day afterward; someone who has it at 1 PM has to break their afternoon in half.
Anchor on the person who has the least flexibility
If one of your participants only has overlap with the rest of the group during their late evening (say, your APAC teammate when the rest of the team is in EMEA), use them as the first row. The grid is easier to scan when the anchor's hours are the ones you're trying to be considerate of.
Plan a few weeks out — and re-check before sending the invite
Daylight saving transitions in March and November can shift your golden window by an hour. If you're scheduling a recurring meeting that crosses one of those dates, re-run the planner with the post-transition date to confirm.
Use the "Copy time" button
Pasting 09:00 NYC · 14:00 London · 22:00 Tokyo into Slack or a calendar invite is faster than writing it out yourself, and it gives every recipient their own local time without ambiguity. No more "is that 9 PM your time or mine?"
When there's no green window, be honest about it
If the planner says "no fully-overlapping working hours," you have a real problem — not a math problem. Either someone takes a call outside working hours, or you switch to async (recorded video, written updates). The planner just makes the constraint visible.