The calculated distance (air line) between Veliko Tŭrnovo and Svishtov is approximately 40 miles respectively 64 kilometers.
By car or train, the actual journey to Svishtov is certainly longer, as only the direct route (as the crow flies) between Veliko Tŭrnovo and Svishtov has been calculated here.
Air line (approximately)
64 kilometers
34 nautical miles