The calculated distance (air line) between Jyväskylä and Lappeenranta is approximately 115 miles respectively 185 kilometers.
By car or train, the actual journey to Lappeenranta is certainly longer, as only the direct route (as the crow flies) between Jyväskylä and Lappeenranta has been calculated here.
Air line (approximately)
185 kilometers
100 nautical miles