The calculated distance (air line) between Sing Buri and Nakhon Sawan is approximately 59 miles respectively 95 kilometers.
By car or train, the actual journey to Nakhon Sawan is certainly longer, as only the direct route (as the crow flies) between Sing Buri and Nakhon Sawan has been calculated here.
Air line (approximately)
95 kilometers
51 nautical miles