The calculated distance (air line) between Thākurgaon and Naksalbāri is approximately 48 miles respectively 77 kilometers.
By car or train, the actual journey to Naksalbāri is certainly longer, as only the direct route (as the crow flies) between Thākurgaon and Naksalbāri has been calculated here.
Air line (approximately)
77 kilometers
41 nautical miles