The short answer: Nepal sets its clocks by a line of longitude (86°15′ east) near the mountain Gauri Shankar, about 100 km east of Kathmandu. That line works out to 5 hours 45 minutes ahead of Greenwich (UTC+5:45). India sets its clocks by a line at 82°30′ east (UTC+5:30), so Nepal comes out 15 minutes ahead.
Ever looked at a collection of clocks marking time from around the world? You may have noticed that Nepal is 15 minutes ahead of its border neighbor India, and 45 minutes off from the whole-hour time zones most of the world uses.
Three's Company
Only three time zones are offset from Coordinated Universal Time (UTC) by 45 minutes: Nepal Standard Time, New Zealand's Chatham Islands (UTC+12:45) and an unofficial zone around Eucla in Western Australia (UTC+8:45). Nepal is the only country that keeps its national time this way. The history behind it is quite unusual.
Keeping Time in Old Nepal
An article from the Nepali Times points out that before the standardized time reckoning, time was kept in Nepal as such:
"In the Malla period, Kathmandu residents had their own traditional way for telling time. If you wanted to know the exact time, you went to a pond near Hanuman Dhoka where an official would tell you how many pala had submerged since dawn. Each pala had a tiny hole and would fill up in exactly 24 minutes. 'This method was OK for us until the Westerners arrived,' explains Sambaraj Acharya, professor at Balmiki Campus."
(In the traditional Nepali count of time, the 24-minute unit is usually called a ghadi, and a pala is one sixtieth of it, about 24 seconds.)
Time ticks along just fine, why worry about managing it?
With the world "shrinking" due to railway and other travel, there was pressure worldwide to create a standardized time system.
Many countries had various different "local times" throughout their own borders, all with mismatched times, making railway management very complicated.
In October 1884, delegates from 26 countries met in Washington, D.C., for the International Meridian Conference, with the purpose of selecting a prime meridian for the whole world. (I wonder how they decided on what time to start?)
They chose the meridian through the Royal Observatory in Greenwich, London, as zero degrees longitude. The conference didn't draw any time zones itself. Over the following decades, each country chose its own standard time, most of them a whole number of hours from Greenwich (east of Greenwich being plus and west being minus). An hour of time is 15 degrees of longitude, which gives 24 standard meridians around the globe.
That's where we get the abbreviation GMT, standing for Greenwich Mean Time. Today's world clocks count from Coordinated Universal Time (UTC), GMT's modern successor.
Accounts of Nepal's own clock history differ. The Nepali Times dates Nepal Standard Time to 1956, with the meridian at Mt Gauri Shankar, 100 km east of Kathmandu. It wasn't Mt Everest, the paper explains, because Gauri Shankar sat closer to the country's center of gravity, as it were. The international time zone database that phones and computers use has Nepal on India's time from 1920, moving its clocks to UTC+5:45 in 1986. Either way, Nepal has kept UTC+5:45 since 1986.
Nepal could have used the same meridian as India, but that line crosses the country well west of Kathmandu, so Gauri Shankar was selected.
Nepal's Meridian
The country itself lies between about 80°E and 88°E longitude. That puts a difference of about 32 clock minutes (1° of longitude = 4 minutes) between the ends of the country.
Somehow, that makes me think I can time travel, but it doesn't work that way. Sigh.
It means that Nepal is narrow enough for just one time zone.
You would think that the time meridian chosen for Nepal would split the country right in the center so that the sun would be over the middle of the country at noon, but remember, most countries set their clocks by a line on the standard grid, a whole hour or a half hour from Greenwich, not by a line through their own middle.
The half-hour line for this part of the world is the one India uses (82°30′ east), and it crosses Nepal well west of Kathmandu.
Now countries can't go moving their meridian...ahem...well...they can, sort of.
24 Meridians are We
Remember, the standard grid has 24 meridians, an hour apart.
Some countries because of how they were situated, opted for halfway between meridians so their time is 30 min different (India is one of these).
With the half-hour line too far west for Nepal, the next 30-minute jump (90°E, UTC+6) would place it too far east, past Nepal's eastern border. Remember, Nepal has only about 8 degrees of longitude end-to-end, giving it only about 32 minutes across for meridian markers.
So, Nepal chose the next best thing, going halfway to the next line, 15 minutes ahead of India.
Thus Nepal sits at UTC+5:45.
Breaking it down = 5 hours from Greenwich, London + 30 minutes (India's half-hour line, which crosses Nepal too far west) + 15 minutes (halfway to the next line, which lands much closer to Kathmandu).
Neither country uses daylight saving time, so the gap with India stays at 15 minutes all year.
Some think Nepal should adopt the same time as its neighbor India (back 15 minutes).
Others think it's better to leave things as is, and keep the mark of distinction...literally 15 minutes of fame.
While others think it would be pretty cool to go back to the water clock. Counting in the Nepali Times' 24-minute pala, this article took about five to research and write.
Time is a funny thing.
