Kathmandu -the capital city of Nepal is connected by air with Bangkok , Honkong, Shanghai , Lhasa, Chengdu, Osaka , Singapore , Dubai , Doha , Abudhabi, Karachi , Dhaka and Indian cities Delhi , Mumbai, Banglore, Kolkatta and Varanasi.
Royal Nepal Airlines is the national flag carrier. Thai Airways operates daily flights between Bangkok and Kathmandu . Other airlines flying to Kathmandu are Nepal Airlines, Qatar Airlines, Etihad Airways, Fly Dubai, Oman Air, Turkish Airlines, Korean Air, Cathay Pacific Airlines, China Southern Airlines, China Eastern Airlines, Air China, Malaysian Airlines, Air Asia, Indigo Air, Indian Airlines, Jet Airways and Biman Bangladesh.
As Nepal is surrounded from three sides by India, and if you are traveling in India prior to Nepal, you can see if its possible to travel to Nepal via Surface. The popular entry points used by tourist to enter Nepal by surface.
Kakarbhitta is Nepal's eastern border town. People traveling in Sikkim and Darjeeling can enter Nepal via Kakarbhitta. Bhadrapur airport of Eastern lies just half an hour drive from Kakarbhitta and has regular flights operated by domestic airlines of Nepal. In the Indian side, Bagdogra airport lies in one hour driving distance from Kakarbhitta Border.
Sunanuli ( Belahiya)
Gorakhapur Railway Station is located in about 2 hours driving distance from Sunauli and is one of the most used entry points by travelers. Gorakphur has railway connection with major Indian Cities including Delhi and Mumbai. People who are already in Varanasi also enter Nepal via Sunauli. Its 8-9 hours drive from Varanasi to Sunauli.
Kyirong (Rasuwagadhi in Nepal side)
Kyirong border crossing between Tibet and Nepal was traditionally open to Nepali and Chinese passport holders and now it's open to foreign travelers, after closure of Kodari border aftermath of earthquake in April 2015. Kyirong is 465 miles from Lhasa and 119 miles from Tingri. From Kyirong Kathmandu is only 54 miles.