Why Isn’t Every Time Difference a Whole Hour?
Most countries differ from Coordinated Universal Time by whole hours, but not all of them. India is five and a half hours ahead, Nepal 5 hours 45 minutes, and you’ll find half-hour or quarter-hour time zones in several other places too, including Iran, Canada and Australia. We looked into how they came about, and where to keep an eye on them before a trip.
Why UTC+5:30 in India?
In principle, time zones follow each other every 15 degrees of longitude, which equals one hour. India spans nearly 30 degrees from west to east, so geographically it sits on the boundary of two time zones. Indian time is based on the 82.5°E meridian, which passes near Mirzapur in the state of Uttar Pradesh. This line lies exactly halfway between the central meridians of UTC+5 and UTC+6, so neither edge of the country ends up more than an hour away from official time.
How did it come about?
In the 19th century, India's major cities kept their own local time. Bombay ran at roughly UTC+4:51 and Calcutta at UTC+5:53, while the railway companies adopted Madras time, which fell between the two, for their timetables. The British colonial administration introduced a single Indian time of UTC+5:30 from January 1, 1906, which also applied to what was then Ceylon, today's Sri Lanka. After independence in 1947, India made it the official time for the whole country, although Calcutta and Bombay held on to their own local time for a few more years.
Pakistan, which split from India in 1947, chose UTC+5, which is why the two neighbors are still half an hour apart today.
One time zone for a huge country
Like China, India uses a single official time, and it doesn't observe daylight saving time. The northeastern states feel the downside most: in Assam and Arunachal Pradesh it gets light around 4:30 AM in summer and dark in the late afternoon, while offices and schools start by official time. Tea gardens in Assam have long used an unofficial local time running an hour ahead, known as "tea garden time."
The question comes up in politics regularly as well. In 2018, India's National Physical Laboratory proposed two time zones in a study: the western and central parts would keep UTC+5:30, while the northeast would move to UTC+6:30. No decision has been made on the proposal so far.
Nepal: a 15-minute difference
For a long time, Nepal used the same UTC+5:30 as India. In 1986, however, it moved its clocks forward by 15 minutes, and UTC+5:45 has been its official time ever since. The new time is based on the 86.25°E meridian, which runs through eastern Nepal, east of Kathmandu. The 15-minute shift fits the country's location more closely, and it also signaled that Nepal keeps its own time, independent of India.
Nepal is the only country that uses a 45-minute offset across its entire territory. Apart from Nepal, such a time zone is official only on New Zealand's Chatham Islands, plus a tiny unofficial strip in Western Australia around Eucla.
Where else will you find non-whole-hour time zones?
- Iran: UTC+3:30
- Afghanistan: UTC+4:30
- India and Sri Lanka: UTC+5:30
- Nepal: UTC+5:45
- Myanmar and the Cocos (Keeling) Islands: UTC+6:30
- Eucla, Western Australia (unofficial): UTC+8:45
- South Australia and the Northern Territory: UTC+9:30
- Lord Howe Island, Australia: UTC+10:30, with clocks moving forward by just 30 minutes in summer
- Chatham Islands, New Zealand: UTC+12:45, UTC+13:45 in summer
- Newfoundland, Canada: UTC-3:30, UTC-2:30 in summer
- Marquesas Islands, French Polynesia: UTC-9:30
There have also been a few shorter-lived examples. Venezuela used UTC-4:30 between 2007 and 2016, and North Korea switched to UTC+8:30 from 2015 to 2018, putting it half an hour behind South Korea.
What's the time difference from Hungary?
Half-hour and quarter-hour time zones look strange at first, but in most cases the explanation is simple: a country chose its official time to fit its own geographic position as closely as possible. They still regularly cause headaches for computer systems and for anyone scheduling international meetings.