The calculated distance (air line) between Agios Ioannis Rentis and Kalamata is approximately 106 miles respectively 171 kilometers.
By car or train, the actual journey to Kalamata is certainly longer, as only the direct route (as the crow flies) between Agios Ioannis Rentis and Kalamata has been calculated here.
Air line (approximately)
171 kilometers
92 nautical miles