Unusual Time Zones: Half-Hour Offsets, the Date Line and More
Time zones look like neat vertical stripes on a map, but real zones follow borders, politics and history. That produces some surprising cases that are worth knowing before you plan a call or a trip.
Half-hour and 45-minute offsets
Most zones differ from UTC by a whole number of hours, but several do not:
- India: UTC+5:30 for the whole country.
- Nepal: UTC+5:45, fifteen minutes ahead of India.
- Iran: UTC+3:30.
- Afghanistan: UTC+4:30.
- Myanmar: UTC+6:30.
- Central Australia: UTC+9:30 in South Australia and the Northern Territory in standard time.
- Newfoundland, Canada: UTC−3:30 in winter.
- Chatham Islands, New Zealand: UTC+12:45 in standard time.
The widest spread: UTC−12 to UTC+14
The earliest time zone is UTC+14, used by the Line Islands of Kiribati. The latest is UTC−12, used by uninhabited islands such as Baker Island. Between them lie 26 hours, which means that at certain moments three different calendar dates exist on Earth at the same time.
The International Date Line
The International Date Line is the place where the calendar date changes by one day. It is not a straight line: it bends around countries and island groups so that neighboring places share the same date. Kiribati moved its part of the line in 1995 so that the whole country is on the same day, and Samoa moved to the west side of the line in 2011, skipping 30 December that year entirely.
Big countries, one clock
China spans an area that would normally cover five time zones but uses a single official time, UTC+8. India also uses one zone. Russia, at the other extreme, uses eleven time zones, and the United States uses several zones across the mainland, Alaska and Hawaii. Countries with several zones are the reason you should always name a city, not only a country.
Zones follow borders, not meridians
Much of mainland Spain lies at the same longitudes as the UK and Portugal, yet it uses Central European Time to stay aligned with France and the rest of Central Europe. Time zone boundaries often follow state or provincial lines, which can create awkward situations where a city is in one zone and a town a few kilometers away is in another.
Where the names come from
Software identifies time zones with the IANA time zone database, using names like Asia/Kolkata or America/Sao_Paulo. Each name represents a region whose clocks have followed the same rules since 1970. The database is updated several times a year as governments change their rules, and browsers include a copy. Time Atlas World reads that copy, which is why it can show many time zones beyond the major cities.
Explore: search for Kathmandu, Kolkata or St Johns on the World Clock to see these offsets live.
Related guides
Time Zones in the United States: Zones, DST and Exceptions
The US time zones from Eastern to Hawaii, when clocks change, which places skip daylight saving time, and how to schedule calls between coasts.
Time Zones in Europe: WET, CET, EET and the Exceptions
Europe uses three main time zones. Learn which countries use which, when clocks change, and which places, such as Iceland and Turkey, do not follow the pattern.
Time Zones in Asia and the Pacific: A Regional Guide
How time zones work across Asia and Oceania: China and India on one clock, multi-zone countries, half-hour offsets and the few places with daylight saving.