Traditionally, the coefficients have been obtained using experimental measurements according to AHSRAE Standard 120, a process which is time consuming and expensive. An alternative is to use CFD, but this has uncertainty due to the approximations used in modeling turbulence. This study estimated that the pressure loss coefficients of duct fitting(elbow, tee) by turbulence model(Standard k-ε, Realizable k-ε, RSM, SST k-ω) using CFD techniques. The results show that Realizable k-ε model could accurately predict the pressure loss coefficients from all cases.