The calculated distance (air line) between Belo Horizonte and Ouro Preto is approximately 43 miles respectively 69 kilometers.
By car or train, the actual journey to Ouro Preto is certainly longer, as only the direct route (as the crow flies) between Belo Horizonte and Ouro Preto has been calculated here.
Air line (approximately)
69 kilometers
37 nautical miles