The calculated distance (air line) between Duisburg and Bad Homburg vor der Höhe is approximately 116 miles respectively 187 kilometers.
By car or train, the actual journey to Bad Homburg vor der Höhe is certainly longer, as only the direct route (as the crow flies) between Duisburg and Bad Homburg vor der Höhe has been calculated here.
Air line (approximately)
187 kilometers
101 nautical miles