The calculated distance (air line) between Oud-Beijerland and Leeuwarden is approximately 112 miles respectively 180 kilometers.
By car or train, the actual journey to Leeuwarden is certainly longer, as only the direct route (as the crow flies) between Oud-Beijerland and Leeuwarden has been calculated here.
Air line (approximately)
180 kilometers
97 nautical miles