World Clock — current time around the world

How to use World Clock

Find the city you care about, or the nearest large city in the same zone. Read its current time against yours — the offset between them is what you will be working with all week. Note whether it is a different calendar day. This is where the real mistakes happen.

Check again after any daylight saving change, because the offset you memorised in January may not hold in July.

The day boundary is the trap

Almost everyone gets the hours right and the date wrong. A Friday afternoon meeting in one place can be Saturday morning in another, and "tomorrow at nine" means two different days to two people on the same call.

The fix is a habit rather than a tool: whenever you name a time to someone in another zone, name the day and the zone with it. "Tuesday 09:00 your time" is unambiguous. "Nine tomorrow" is a coin toss.

Everyone learns the day boundary the same way — by joining a call twenty-four hours late and finding the room empty and very quiet.

Offsets are not fixed

The gap between two cities is not a constant. It changes whenever either place starts or ends daylight saving, and they rarely do it on the same date — or in the same direction, since the southern hemisphere runs opposite to the northern.

Two cities can be five hours apart for most of the year and four for a few weeks. Some places do not observe daylight saving at all, so their offset to everyone else shifts twice a year without them changing anything.

Not every offset is a whole number of hours; several zones sit on the half hour, and a few on the quarter. A single country can span several zones, which is why "time in the US" is not a question with one answer.

Working across zones without misery

Find the overlap once and write it down. For any two locations there is a band of hours that is civilised at both ends, and it is usually narrower than you hope — sometimes two hours, sometimes none at all. Knowing that band saves you from re-deriving it before every meeting.

When the overlap is genuinely empty, someone is taking an inconvenient hour, and the fair arrangement is to alternate who. Teams that never discuss this always end up with the same person on the late call forever, and that person notices.