Choosing the cities for your world clock

Most world clocks are decorative. They show a dozen famous cities in no particular order, and the owner glances at them roughly never. A world clock earns its place on a screen or a wall only when it answers a question you actually have several times a week: is it a decent hour to contact this person, and how long until it is?

Start from your obligations, not the map

Write down the places you wait on. A supplier in Shenzhen, a client in Chicago, a sibling in Melbourne, the market that opens before yours. That list is usually shorter than you expect and rarely matches the list of largest cities. If a place is not somewhere you contact, coordinate with or worry about, it is decoration.

Four to eight entries is the range where a world clock stays readable. Beyond that you stop scanning it and start searching it, at which point a converter is the better tool.

Order them west to east, always

A world clock is much easier to read when the times run in one direction. Ordering the cities from west to east means the clock reads like a wave: the earliest hours on one side, the latest on the other, and the day sweeping across as time passes. Alphabetical order destroys that and forces you to read each entry individually.

Pick the city that owns the zone

For each place, choose the city people would name, not the nearest one to you. "Los Angeles" is understood everywhere, where a smaller Californian city is not, even though the clock is identical. This matters most when you share the clock or screenshot it, because the label is doing the communicating and the digits are only confirming it.

Where a country spans several zones, name the specific city rather than the country. The time in "the United States" is four different answers on the mainland alone, and more with Alaska and Hawaii.

Include your own city

It sounds redundant. It is not. Having your own reading in the same row of digits, in the same format, is what turns the clock from a lookup into a comparison: you see the gap instead of computing it. It is also the entry that makes screenshots useful to other people.

Decide about seconds and about the 24-hour clock

Seconds are motion, and motion draws the eye to a clock you are trying to ignore. Unless you are coordinating something to the second, leave them off. The 24-hour clock is worth using even if your country writes am and pm, because it removes the single most common misreading: a colleague's 7 that turns out to be the wrong 7.

Then check it during a clock change

A clock built in July will look different in November, and that is the point at which a badly chosen set of cities becomes confusing rather than useful. Once you have your set, build it in the world clock, keep the link, and look at it again after the next changeover to make sure it still tells you what you wanted to know.