The calculated distance (air line) between Sa Dec and Thủ Dầu Một is approximately 77 miles respectively 124 kilometers.
By car or train, the actual journey to Thủ Dầu Một is certainly longer, as only the direct route (as the crow flies) between Sa Dec and Thủ Dầu Một has been calculated here.
Air line (approximately)
124 kilometers
67 nautical miles