Want to take a side trip from India to Nepal? It's a popular thing to do and there are a number of ways to go about it, depending on how much money you're prepared to spend. This guide outlines the best options for travel.
Do note that Indian citizens don't require a visa to enter Nepal. However, if traveling by air, Indian citizens must show a valid passport or Voter ID when checking in, and at immigration. Aadhar Card is not a satisfactory form of identification. If traveling overland, other forms of government-issued identification can be used at border crossings. However, it's likely that no one will even be bothered to check!
Foreigners can obtain a Nepali tourist visa on arrival at the airport in Kathmandu. Nepali tourist visas are also available from immigration at land border crossings that are open to foreigners. In addition to your passport, you'll need passport-sized photos and possibly foreign currency (some crossings insist on payment in US dollars).
If you want to fly (and get some incredible Himalayan views), Delhi to Kathmandu is the least expensive route by air to Nepal. Otherwise, the best option is to take a train to Gorakhpur and then a bus. Taking the bus all the way has become slightly more appealing since the Delhi Transport Corporation launched a direct service to Kathmandu in late 2014. However, it's still a really long 30-hour haul!
Many people travel overland from Varanasi to Kathmandu -- either by bus, or train and bus combination. It takes less time than overland from Delhi. It's also possible to fly. However, it's much costlier than from Delhi and there are very few direct flights.
Kolkata to Kathmandu
Nepal-based Buddha air operates three direct flights a week from Kolkata to Kathmandu -- on Mondays, Wednesdays and Fridays. The flights depart at 9.05 a.m. and the flight time is about 90 minutes. Expect to pay about 20,000 rupees one way. It's expensive! Air India is a cheaper option with direct flights costing about 7,500 rupees. Alternatively, you can go by land via the Raxaul or Panitanki borders (see below).
Most people going overland from north India to Nepal pass through the Sunauli border to Bhairahawa in central Nepal, accessible from rather unappealing Gorakhpur in Uttar Pradesh (although, pleasingly, Gorakhpur has become a lot cleaner in recent years). This is the biggest and busiest India-Nepal border crossing. There are frequent connections to Kathmandu, Pokhara, and Lumbini from there.
Via the Raxaul Border Crossing
The Raxaul border crossing to Birganj in central Nepal is accessible from Patna in Bihar. It's most convenient for anyone traveling from Bodh Gaya or Kolkata. There are direct trains from Kolkata to rather grim Raxaul (16 hours). From Bodh Gaya, it's quicker to take a bus or car and travel by road (eight hours) as opposed to train (13 hours). From the border, buses take six to seven hours to reach Kathmandu and eight hours to Pokhara. Shared jeeps to Kathmandu are a quicker option and only take four to five hours.
The Panitanki border crossing, to Kakarbhitta in far eastern Nepal, is accessible from Siliguri in West Bengal. It's most utilized by people traveling from Darjeeling, Kolkata, Sikkim and the rest of northeast India. Buses, taxis and shared jeeps run to the border from Siliguri, Kalimpong, and Gangtok in Sikkim. Siliguri to Panitank (for those going from Darjeeling) takes approximately 45 minutes to an hour. The border crossing is open 24 hours, and is quiet and simple. It kinds of feels like being in the middle of nowhere! Foreigners should ensure that they arrive before 10 p.m., when the Indian and Nepali immigration offices close. There are regular buses to Kathmandu (14 to 16 hours) and Pokhara (15 hours) from Kakarbhitta. It's worth stopping at Chitwan National Park on the way to break the journey. Get off the bus at Sauraha (nine hours from Kakarbhitta), which is the closest town and travel hub to the park.
Via the Banbasa Border Crossing
This border crossing, at Banbasa in Uttarakhand, is the most westerly crossing into Nepal from India. It's the quickest, and most rural, route from Delhi to Kathmandu. Yet, it's still a long way from Mahendra Nagar (now officially called Bhimdatta) on the Nepali side of the border to Kathmandu. Buses take about 15 to 17 hours. Banbasa can be reached from Barielly, Rudrapur, or Haldwani in Uttarakhand (three hours). It's possible to get buses to Pokhara and Kathmandu from Mahendra Nagar. If you're not short on time, it's worth visiting Bardia National Park on the way (get off at Ambassa, about five hours from Mahendra Nagar. Thakurdwara is the closest village to the park and it's about 40 minutes from Ambassa).
Other Border Crossings
Two other border crossing points (from Jamunaha in Uttar Pradesh to Nepalganj in western Nepal, and Gauriphanta in Uttar Pradesh to Dhanghadi in far western Nepal) are open to tourists. However, they're difficult to reach and rarely used. Non-official border crossings at Janakpur, Biratnagar and Ilam rarely allow foreign tourists.