The calculated distance (air line) between Donostia / San Sebastián and Azpeitia is approximately 17 miles respectively 28 kilometers.
By car or train, the actual journey to Azpeitia is certainly longer, as only the direct route (as the crow flies) between Donostia / San Sebastián and Azpeitia has been calculated here.
Air line (approximately)
28 kilometers
15 nautical miles