The calculated distance (air line) between Nowe Miasto Lubawskie and Częstochowa is approximately 182 miles respectively 294 kilometers.
By car or train, the actual journey to Częstochowa is certainly longer, as only the direct route (as the crow flies) between Nowe Miasto Lubawskie and Częstochowa has been calculated here.
Air line (approximately)
294 kilometers
158 nautical miles