The calculated distance (air line) between Sępólno Krajeńskie and Olsztyn is approximately 124 miles respectively 199 kilometers.
By car or train, the actual journey to Olsztyn is certainly longer, as only the direct route (as the crow flies) between Sępólno Krajeńskie and Olsztyn has been calculated here.
Air line (approximately)
199 kilometers
107 nautical miles