The calculated distance (air line) between Kościerzyna and Bydgoszcz is approximately 69 miles respectively 111 kilometers.
By car or train, the actual journey to Bydgoszcz is certainly longer, as only the direct route (as the crow flies) between Kościerzyna and Bydgoszcz has been calculated here.
Air line (approximately)
111 kilometers
60 nautical miles