The calculated distance (air line) between Golub-Dobrzyń and Białystok is approximately 170 miles respectively 274 kilometers.
By car or train, the actual journey to Białystok is certainly longer, as only the direct route (as the crow flies) between Golub-Dobrzyń and Białystok has been calculated here.
Air line (approximately)
274 kilometers
148 nautical miles