The calculated distance (air line) between Phnom Penh and Rạch Giá is approximately 108 miles respectively 173 kilometers.
By car or train, the actual journey to Rạch Giá is certainly longer, as only the direct route (as the crow flies) between Phnom Penh and Rạch Giá has been calculated here.
Air line (approximately)
173 kilometers
94 nautical miles