Viscosity at the liquidus temperature (T-L),eta(L), is a critical parameter for the design of new glasses, particularly for industrial glass production where crystallization must be suppressed. However, a direct viscometric determination of eta(L)for a glass-forming system is difficult due to crystallization. Here we propose an alternative approach for determining eta(L)through differential scanning calorimetry (DSC). Specifically, DSC is used to measure both the viscosity curve and liquidus temperature of a glass-forming system and then derive its eta(L)value. The eta(L)values determined using DSC are found to be in excellent agreement with those measured through viscometry. The DSC approach is applicable to various glass-forming systems covering a wide range of fragilities and eta(L)values spanning over five orders of magnitude. Other advantages of this approach are its accuracy and small sample requirements.