There are plenty of flights to Kathmandu starting from Delhi, Goa, Ahmedabad, Bengaluru, Mumbai, Varanasi, Hyderabad, and Kolkata. Royal Nepal Airlines, Air India, Jet Airways and IndiGo provide directs flights. The flight departs from Delhi to Kathmandu costs about INR 9, 100. You can check the price online to obtain a ticket. Then you can take a flight or road journey to Tibet. There is currently no train from Kathmandu to Tibet.
Kathmandu to Lhasa by flight
There are two flights a day from Kathmandu to Lhasa, provided by Air China, and Sichuan Airlines. The flight costs about US$300(22324INR) and it takes 1 to 30 hours. And there is an additional advantage that when the plane flies over the Himalayas, you can get a bird's eye view of the summit of Mount Everest.
Kathmandu to Lhasa by land
The land trip from Nepal to Tibet is an incredible journey via the border between Tibet and Nepal, and the distance is around 1120km. From the lowland valleys of Kathmandu to the highlands of the mighty Himalayas, you will visit Mount Everest and the holiest Mount Kailash for Indian Hindus. Then get across the plains and prairies, see the sparkling lakes, finally travel to the holy city Lhasa - the religious and cultural center of Tibet. It usually takes 3 to 4 days, and you will have time to see the amazing sights on the plateau and enjoy the magnificent landscape.
Delhi to Kathmandu
Visitors who travel to Tibet from India
by flight only spends 1 hour and 45 minutes. A direct flight from Nepal Airlines RA218 (19:40-21:40) costs about US$90(6,697 INR). Due to the close distance between the two countries and the short flight duration, the cost of flying from India to Kathmandu is relatively lower. Nepal is also the preferred gateway for Indian passport holders to enter Tibet because there is visa-free travel between India and Nepal. They do not need a passport or visa to enter Nepal and only need a government-issued ID card.