The calculated distance (air line) between Sandanski and Veliko Tŭrnovo is approximately 159 miles respectively 256 kilometers.
By car or train, the actual journey to Veliko Tŭrnovo is certainly longer, as only the direct route (as the crow flies) between Sandanski and Veliko Tŭrnovo has been calculated here.
Air line (approximately)
256 kilometers
138 nautical miles