The calculated distance (air line) between Laem Sing and Krathum Baen is approximately 147 miles respectively 236 kilometers.
By car or train, the actual journey to Krathum Baen is certainly longer, as only the direct route (as the crow flies) between Laem Sing and Krathum Baen has been calculated here.
Air line (approximately)
236 kilometers
127 nautical miles