If you want to enter Bhutan by road via Indian state of West Bengal, you will first arrive in town of Phuentsholing in south-west located approximately 164 km east of the Indian national airport at Bagdogra. After crossing Phuentsholing, you begin your journey to Thimphu, the capital city with travel time of about six hours for the 164 km stretch.
If you want to enter Bhutan by road via Indian state of Assam, you will first arrive in Samdrupzongkhar, which is 115 Km from Guwahati Airport in Assam. Or you can also enter the town of Gelephu, 244.3 Km from Guwahati Airport.
By Air you will land in Paro International Airport, the only international airport in Bhutan situated at a height of 2,225 m (7300 ft) above sea level and is surrounded by mountains as high as 4,876 m (16,000 ft). At present two carriers operate to Bhutan, Drukair and Bhutan Airlines. And there are domestic airports in Yonphula in eastern Bhutan, Bumthang in central Bhutan, and Gelephu in Southern Bhutan.
There are flights to destinations like Bangkok, Delhi, Kolkata, Bagdogra, Bodh Gaya, Dhaka, Kathmandu, Guwahati, Singapore and Mumbai.