Timezone Map
A world map with two layers you can toggle: time zones coloured by UTC offset, and the live day/night terminator computed from the current solar position. Scroll or drag to explore.
Countries coloured by UTC offset, plus hourly meridians.
Night hemisphere and the subsolar point, updated every minute.
Marks major cities on the map.
Legend
Scroll to zoom, drag to pan. On touch screens, drag to pan and use the buttons to zoom.
Colours use one representative zone per country, so countries spanning several zones — the United States, Russia, Canada, Australia, Brazil — appear in a single colour. The hourly meridians show the underlying grid.
Boundaries: Natural Earth (public domain), via world-atlas.
What this map shows
Time zones by offset
Every country is filled by its current UTC offset, so the colour already accounts for daylight saving wherever it is in effect.
A real terminator
The night hemisphere is derived from the solar declination and subsolar longitude for the current moment, not a static picture.
Loaded only when needed
Country geometry is a static file fetched on demand and cached by your browser. It never enters the JavaScript bundle of any other page.
Frequently asked questions
Why is a large country shown in one colour?
The map is drawn at country granularity, so each country uses one representative time zone. The United States, Russia, Canada, Australia and Brazil actually span several — the hourly meridian lines are there to make that visible.
How is the day/night boundary calculated?
From the sun position: the solar declination and the subsolar longitude for the current UTC time give the latitude of the terminator at every meridian. The bright dot marks the point where the sun is directly overhead.
Does the map update by itself?
Yes, once a minute. That is enough for the terminator, which moves roughly a quarter of a degree per minute, and it keeps the page from doing needless work.
Where does the map data come from?
Country outlines are Natural Earth data (public domain) at 1:110m resolution, simplified at build time into a plain SVG path file so the browser needs no projection or topology library.