Mercator – World Clock Watch

Mercator is a world clock watch face for Wear OS with multiple time zones on a full-face map, built for the Samsung Galaxy Watch, for people who want the map and nothing in its way. The world fills the face, in the shape you know from every web map, with your home at the centre. Europe and North America come out about a half larger than on a flat strip. Day and night are painted on the map as they really fall, with the real twilight band, and the shading moves across it once a day while the map stands still. Or set the map moving instead: the sun stays in the middle and the world slides under it.

Your local time and date sit above the map. Three world zones of your choice sit along the bottom of the map, over the Southern Ocean, each as its hour over its name with +30m and +1d markers when they apply. Each is an orange pin at its city, home a white one, so you see where a place is and whether it is in daylight. Along the top of the map, over the Arctic, the hour numerals ride with the sun. A dashed line marks the International Date Line, and fine red slashes, with the night showing through, and a +1d or -1d mark the part of the world that is on a different date from you.

No shortcut chips, no moon, no complications: the map is the point. The battery appears under the zones only at 100% or at 15% and below.

On the day of a total or annular solar eclipse the path of the shadow is drawn across the map, and the shadow itself crosses it during the eclipse (2027 to 2035).

Settings, all on the watch (hold the face, tap Customize):
• Map motion: fixed, with home at the centre (the default), or sliding under the sun
• Map style: vintage atlas or dark; the dark map is also what you see in always-on mode
• Zone 1, 2 and 3: off, or any of 72 time zones, every inhabited one on Earth
• Home: your own place, for your pin and the centre of the map. While you choose it in Customize, its code (MTX, NYC) shows in red beside 100%; on the face it shows whenever the battery is full
• Date change: Tint and +1d (the red slashes and the label), Tint only, or Line only

Your own zone is never a setting: it follows the watch. Daylight saving changes on its own, per zone, through 2036.

Mercator is built in the Watch Face Format: no phone app, no account, no network access, and no data collected. Coastlines from Natural Earth, public domain.

Requires Wear OS 6 or later. Tested on the Galaxy Watch 7. One-off purchase, no subscription.

Setup guide: worldclockwatch.com/setup.html
Support: worldclockwatch@gmail.com