The calculated distance (air line) between Lan Sak and Krathum Baen is approximately 132 miles respectively 213 kilometers.
By car or train, the actual journey to Krathum Baen is certainly longer, as only the direct route (as the crow flies) between Lan Sak and Krathum Baen has been calculated here.
Air line (approximately)
213 kilometers
115 nautical miles