There are two possibilities to enter/exit Bhutan, by air with Bhutan’s national airline (Druk-Air) and overland from north-east of India from west-bengal state.

Druk-Air is the only carrier that operates flights to Paro, (only airport in Bhutan) and it’s destinations are to the following cities:

Bangkok, Delhi, Kolkota, Bagdogra, Gaya, Kathmandu & Dacca. One can connect your International flight to Bhutan from any of the above cities.

The only entry into Bhutan overland is from Phuntsholing, the border town of Bhutan which is 3 hrs drive from Bagdogra airport in West-Bengal state. There are flights to Bagdogra from Delhi, Kolkota, Mumbai & Gauhati (Domestic flights within India). From Bagdogra is only 2 hrs to Darjeeling & 2 hrs to Sikkim also. That’s if one is interested to combine the tour to Bhutan with Darjeeling and Sikkim.

Optional exit from Bhutan is also possible from Samdrupjongkhar, south-east Bhutan to Gauhati in Assam. From Gauhati one can fly to Delhi, Kolkota, Mumbai & Bagdogra. Exiting Bhutan from south-east saves you driving all the way  back on the same road to either Paro or Phuntsholing in south-west Bhutan.