The calculated distance (air line) between Korsun-Shevchenkivskyy and Pereiaslav is approximately 46 miles respectively 74 kilometers.
By car or train, the actual journey to Pereiaslav is certainly longer, as only the direct route (as the crow flies) between Korsun-Shevchenkivskyy and Pereiaslav has been calculated here.
Air line (approximately)
74 kilometers
40 nautical miles