The measurement of methane potential during anaerobic digestion has generally been accomplished through batch assays. Yet, the majority of industrial plants employ a semi-continuous feeding regime and the estimation of continuous process yield from batch data is not straightforward due to differences in kinetic rates. A simple method is examined whereby batch assays were set up with very high inoculum-to-substrate ratios (I:S) and the results applied to a model of mass flow through a continuous process. The results demonstrate that high I:S batch assays estimated the continuous process yield to within 2.5% of the measured value.