The calculated distance (air line) between Samdrup Jongkhar and Trashigang is approximately 37 miles respectively 59 kilometers.
By car or train, the actual journey to Trashigang is certainly longer, as only the direct route (as the crow flies) between Samdrup Jongkhar and Trashigang has been calculated here.
Air line (approximately)
59 kilometers
32 nautical miles