The best direct travel option will be via flight from Tribhuvan International Airport to Paro International Airport. However, bus services are running from Kathmandu to Siliguri in West Bengal and from there you can either take a bus or taxi to reach Phuentsholing in Bhutan.

Nepal and Bhutan share their borders with Sikkim and Siliguri districts of West Bengal –to reach Phuentsholing or Paro from Nepal, you have to cover the overland route. Bhutan to Nepal distance is only about 63 kilometres. The journey, however, is of about 404 kilometres on a flight or in case of road journey, around 180 kilometres from Siliguri (after reaching from Nepal) to Phuentsholing.  

The overland bus journey from Nepal to Siliguri and then Siliguri to Phuentsholing is nearly 787 kilometres, of which the distance between Kathmandu and Kakarbhitta is 457 kilometres. Kakarbhitta is the border town of Nepal and closest to Siliguri –from Kathmandu, a direct bus journey to Kakarbhitta will take more or less 10 hours.