The calculated distance (air line) between Frankfurt am Main and Marburg an der Lahn is approximately 48 miles respectively 77 kilometers.
By car or train, the actual journey to Marburg an der Lahn is certainly longer, as only the direct route (as the crow flies) between Frankfurt am Main and Marburg an der Lahn has been calculated here.
Air line (approximately)
77 kilometers
42 nautical miles