Four methods of determining optimum coagulation levels in tofu manufacture were compared. Full-fat soyflakes were used to produce 5% solids soymilk. Each soymilk batch was coagulated with calcium sulfate dihydrate (0.000–0.0450 N). Electrical conductance of the coagulating batches was recorded at 72°C and 21°C. Coagulated batches were pressed to make tofu and whey volume, pH, transmittance (400 nm) and tofu composition were measured. Whey transmittance and conductance correlated with coagulant concentration (r=0.87). Tofu yield, conductivity, and absorbance data were also related. Measuring the conductance of the coagulating soymilk was faster than obtaining pH and spectrophotometric values. Conductivity and transmittance could be used to optimize tofu coagulation.