TIME ATLASWORLDThe world's time, at a glance

Half-Hour Time Zones, 45-Minute Offsets and the Date Line

Last updated October 14, 2026 · Written by with AI assistance, fact-checked against official sources.

Quick answer. Several places are not a whole number of hours from UTC. India, Sri Lanka, Iran, Afghanistan, Myanmar, central Australia and Newfoundland use half-hour offsets, and Nepal and New Zealand's Chatham Islands use 45-minute offsets. The clocks also run from UTC−12 to UTC+14, so for a few hours each day three different dates are in use at once.

On a map, time zones look like vertical stripes. Real zones follow borders and political decisions, which produces cases 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:

Cities with unusual UTC offsetsHonolulu UTC−10; St. John's UTC−3:30 in January, UTC−2:30 in July; London UTC+0 in January, UTC+1 in July; New Delhi UTC+5:30; Kathmandu UTC+5:45; Darwin UTC+9:30; Adelaide UTC+10:30 in January, UTC+9:30 in July; Chatham Islands UTC+13:45 in January, UTC+12:45 in July; Kiritimati UTC+14−8−40+4+8+12Honolulu−10St. John's−3:30 / −2:30London+0 / +1New Delhi+5:30Kathmandu+5:45Darwin+9:30Adelaide+10:30 / +9:30Chatham Islands+13:45 / +12:45Kiritimati+14
Half-hour and 45-minute offsets sit between the whole-hour lines. Kiritimati is the earliest example in the list, at UTC+14. Filled dot: January. Hollow dot: July, drawn only where daylight saving changes the offset.

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. In a country with several zones, a time without a city is incomplete.

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.

Search for Kathmandu, Kolkata or St Johns on the World Clock to see these offsets live.

Frequently asked questions

Which places use a 45-minute offset?

Nepal uses UTC+5:45, and the Chatham Islands of New Zealand use UTC+12:45 in winter and UTC+13:45 in summer. A small area around Eucla in Western Australia also follows UTC+8:45 by local custom.

Which place is the first to start a new day?

The Line Islands of Kiribati, including Kiritimati, at UTC+14. They reach midnight 26 hours before the last inhabited places at UTC−12 and UTC−11.

Why does China use only one time zone?

Since 1949 the whole country has used Beijing time (UTC+8), although it is wide enough for about five zones. In the far west the sun can rise as late as 10 a.m. by the clock in winter.

Sources

Keep reading

By region

Asia Time Zones: UTC Offsets by Country and the Pacific

Asian countries use offsets from UTC+2 to UTC+9, with odd ones like India (UTC+5:30) and Nepal (UTC+5:45). Offsets by country, and the Pacific.

Read guide →Basics

UTC Offset Explained: UTC vs GMT, and How to Convert Time

A UTC offset like UTC−5 is one number. A time zone like America/New_York is a set of rules that changes it. How to read offsets and convert between cities.

Read guide →