Between 70% and 80% of South Africa’s beef is produced through feedlots. It is therefore important that the commercial beef cattle farmer that markets weaner calves, takes note of the biological factors that determine feedlot profit. Performance is very important and if he pays attention to these factors, he can get higher prices for his weaner calves. The factors that influence feedlot profit can be divided into biological factors (carcass weight, deaths and diseases, weaning weight, feed intake, feed efficiency, carcass classification and days in the feedlot) and the feedlot industry’s margins that are dependent on the input prices (mainly weaner and feed prices). When feedlots purchase calves, they mainly rely on perception, experience or use their gut feeling. It is important that feedlots procure calves with good genetic merit that fit the goals of the feedlot and producers should supply such information. In addition, it is also important to note that, the weaner calf and grain prices are also important factors that affects feedlot profit. Other methods to identify the potential performance of feedlot calves, e.g. a production profile classification system, is also being investigated.