In forced-convection furnaces for reheating Al-alloys, convective heat transfer mechanism dominates. Al-body temperature prediction model uses measured furnace temperature as boundary condition. To calibrate such model, a convective heat transfer coefficient h is to be determined. Optimization technique is used here to determine h for every measured temperature sample so that measured temperatures match calculated, supposing radiative heat transfer coefficient constant and neglecting conductive heat transfer. Obtained h stably converges during normal reheating conditions. The obtained model is 4-fold cross-validated and obtained Root Mean Square Error of whole reheating profiles are [7,7; 20,4; 10,4; 12,5] °C.