The calculated distance (air line) between Frankfurt am Main and Oud-Heverlee is approximately 184 miles respectively 295 kilometers.
By car or train, the actual journey to Oud-Heverlee is certainly longer, as only the direct route (as the crow flies) between Frankfurt am Main and Oud-Heverlee has been calculated here.
Air line (approximately)
295 kilometers
159 nautical miles