The objective of this work was to develop and test methods of predicting permeate flux in a spiral-wound ultrafiltration system from experiments run on a small flat membrane module. Two models were based on a traditional mass transfer (Sherwood) correlation and two on resistance theory. Three of the pressure on the permeate flux. Experimentally measured permeate fluxes from skim milk in the spiral-wound unit were compared to model predictions from four correlations fitted to experimental data from the small-scale, flat-membrane system. While all correlations under-predicted flux at low cross-flow velocity and over-predicted at high velocity, the ability of each correlation to predict an average flux was very good, indicating that data from flat-membrane be used, under carefully controlled conditions, to predict a spiral-wound system.