World Time Zones: UTC Offsets, Odd Half-Hours and the Date Line

Offsets, not zones, are what count

Every local clock is set as an offset from Coordinated Universal Time (UTC), the atomic time scale kept by the International Bureau of Weights and Measures. UTC itself never changes for the seasons. When people say "Tokyo is UTC+9", they mean Tokyo clocks read nine hours ahead of UTC all year.

UTC in its current form began on 1 January 1972, taking over from Greenwich Mean Time as the reference for civil time. It is built from atomic clocks, with occasional leap seconds added so it stays within 0.9 seconds of Earth's rotation; the most recent one was inserted on 31 December 2016. In 2022 the General Conference on Weights and Measures resolved to stop adding leap seconds by 2035, which will let UTC drift slowly away from solar time. None of this moves any offset: when UTC changes, every local clock changes with it.

The textbook picture is 24 neat zones, each 15 degrees of longitude wide. Real clocks follow borders and politics instead, and the offsets do not stop at ±12. Using the IANA time zone database (the data behind phones, computers and servers, version 2026e), Beelad counted the standard offset kept by every inhabited zone in 2026:

• 37 distinct standard offsets are in use, from UTC−11 (American Samoa, Niue) to UTC+14 (Kiribati's Line Islands).
• 26 of them are whole hours and 11 are half- or quarter-hour offsets.
• Daylight saving time adds two more that never occur as standard time, UTC−2:30 (Newfoundland in summer) and UTC+13:45 (New Zealand's Chatham Islands in summer), for 39 offsets in all.
• UTC−12 exists, but only for two uninhabited US islands, Baker and Howland.

The 11 offsets that are not whole hours

Most countries picked a whole-hour offset close to their longitude. A few chose a half or quarter hour to keep clock noon closer to solar noon, or to set themselves apart from a neighbor.

Why Nepal is at UTC+5:45

Nepal's standard meridian runs through the peak of Gaurishankar, a mountain about 100 km east of Kathmandu, not through Mount Everest as is often claimed. Nepal used Indian Standard Time (UTC+5:30) from 1920 and moved its clocks forward 15 minutes in 1986. The result is that Nepal runs exactly 15 minutes ahead of India, its largest neighbor.

Countries with the most time zones

Counting overseas territories, France uses more time zones than any other country: 12, from UTC−10 in Tahiti to UTC+12 in Wallis and Futuna, including uninhabited Clipperton Island at UTC−8. Adding its Antarctic claim, Adélie Land, makes 13. Metropolitan France itself has a single zone, UTC+1 (UTC+2 in summer). In the table, zone counts and standard ranges include each country's territories.

Russia is the record holder within its own borders: 11 zones, all on Russian soil, from the Kaliningrad exclave on the Baltic (UTC+2) to Kamchatka and Chukotka (UTC+12). The United States uses six standard zones across its 50 states, from UTC−5 on the East Coast to UTC−10 in Hawaii; its territories add the rest.

Big countries that chose one zone

China has used Beijing time, UTC+8, for the whole country since 1949, even though it spans about 58 degrees of longitude, roughly five geographical time zones. In far-western Xinjiang, many people also use an unofficial local time two hours behind Beijing. India has a single zone, UTC+5:30, across about 3.3 million km².

Kazakhstan is the newest example. It had been split between UTC+5 in the west and UTC+6 in the east, and on 1 March 2024 the eastern half, including the capital Astana, moved its clocks back an hour so the whole country now runs on UTC+5.

The date line and the day Samoa skipped

Countries near the International Date Line choose which side of it to be on, and two Pacific nations have switched sides.

Kiribati straddled the line until the end of 1994, so its eastern and western islands were on different calendar days. It then moved the Line Islands from UTC−10 to UTC+14, putting the whole country on the same date. Kiritimati, in the Line Islands, is now among the first inhabited places to start each new day, and Kiribati alone spans three offsets: UTC+12, +13 and +14.

Samoa followed in 2011, moving to the western side of the line. Clocks went from the end of Thursday 29 December straight to Saturday 31 December, so Friday 30 December 2011 never happened there.

Daylight saving: why Beelad shows standard time

Europe, most of North America, parts of Australia, New Zealand and Chile, among others, move clocks forward in their summer, and the rules change: Egypt brought back daylight saving time in April 2023 after years without it, while Samoa abolished it in 2021. A page that printed "the" offset for London would be wrong for seven months of the year.

So each Beelad country page shows the standard offset, without daylight saving, as one value (Japan: UTC+9) or as a range for countries spanning several zones (Brazil: UTC−3 to UTC−5). The range describes the country's home territory, which is why France shows UTC+1 and not its overseas offsets. For live times that include daylight saving, a phone's world clock uses the same IANA database counted above.

Time zones often come up alongside dialing codes when calling abroad; the guide to international calling codes covers the numbers side.

Key takeaways

• 37 standard UTC offsets are in use in 2026, from UTC−11 to UTC+14; daylight saving brings the total to 39.
• 11 of them are not whole hours, including India's +5:30, Nepal's +5:45 and Chatham's +12:45.
• France has the most time zones (12) because of its overseas territories; Russia has the most within one territory (11).
• China, India and, since March 2024, Kazakhstan each use one zone despite their size.
• For scheduling, convert through UTC and check whether either side is on daylight saving that day.