Which time zone has the most unusual offset?

The Chatham Islands at UTC+12:45, rising to UTC+13:45 in daylight saving, are the most extreme regularly used example. Nepal at UTC+05:45 is the other well-known quarter-hour offset.

Why does India use a single time zone?

It is a deliberate choice for national coherence despite spanning about two hours of solar time. The compromise offset of UTC+05:30 means the far east and far west of the country both live somewhat out of step with the sun.

Are there any offsets that are not multiples of 15 minutes?

Not in current use. Historically, before standard zones, local mean times were set by longitude and produced arbitrary offsets — which is precisely the messiness that standard time zones were introduced to remove.

Why some time zones use 30 or 45 minute offsets

The tidy picture of 24 one-hour bands is a simplification. A significant share of the world runs on a half-hour offset, and a few places use quarter-hour offsets that break almost every naive assumption about clocks.

Last updated 2026-08-04 · Written by the NowZones publisher in Denmark. Offsets and DST examples use the IANA Time Zone Database via the same libraries as the city clocks. This is editorial explanation, not legal, medical, or aviation advice.

Where the fractional offsets are

Half-hour offsets cover a large population. India and Sri Lanka use UTC+05:30, Iran UTC+03:30, Afghanistan UTC+04:30, Myanmar UTC+06:30, and central Australia UTC+09:30. In the Americas, Newfoundland runs at UTC−03:30 and the Marquesas Islands at UTC−09:30.

Quarter-hour offsets are rarer. Nepal uses UTC+05:45, and New Zealand's Chatham Islands use UTC+12:45, moving to UTC+13:45 during their daylight saving period.

Some regions have moved between the two. North Korea shifted from UTC+09:00 to UTC+08:30 in 2015 and back to UTC+09:00 in 2018, which is a good reminder that these values are political decisions rather than fixed geography.

Why a country would choose one

The usual reason is compromise. India spans roughly 28 degrees of longitude, which is about two hours of solar time, but uses a single zone. Splitting the country was politically unattractive, so the national clock was set near the 82.5°E meridian — half an hour off the whole-hour lines on either side.

Sometimes the motivation is to be distinct. Nepal's offset is aligned to a meridian near Kathmandu, which also has the effect of setting the country apart from Indian time by fifteen minutes.

Geography plays a part too. A region sitting squarely between two hour bands has no whole-hour choice that matches local solar noon well, and a half-hour offset is simply the better fit.

What breaks

Code that stores offsets as whole hours is wrong for a large part of the world. Offsets must be handled in minutes — or better, not stored at all, with a zone identifier used instead.

Interfaces that let people pick "UTC+5" or "UTC+6" from a dropdown quietly exclude India, Iran, Nepal, and everyone else on a fractional offset. A city or zone picker avoids the problem entirely.

Mental arithmetic gets harder too. When the gap between two cities is 4 hours 30 minutes, the minutes change as well as the hour, and it is easy to convert only the hour and be half an hour out.

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Frequently asked questions

Which time zone has the most unusual offset?: The Chatham Islands at UTC+12:45, rising to UTC+13:45 in daylight saving, are the most extreme regularly used example. Nepal at UTC+05:45 is the other well-known quarter-hour offset.
Why does India use a single time zone?: It is a deliberate choice for national coherence despite spanning about two hours of solar time. The compromise offset of UTC+05:30 means the far east and far west of the country both live somewhat out of step with the sun.
Are there any offsets that are not multiples of 15 minutes?: Not in current use. Historically, before standard zones, local mean times were set by longitude and produced arbitrary offsets — which is precisely the messiness that standard time zones were introduced to remove.