Fertilizers are major raw materials for microalgae cultivation. This study aims to reduce the cost of fertilizers and to enhance economic viability. The focus is on urea, potassium dihydrogen phosphate, and heptahydrate magnesium sulfate, which provide the main elements for algae cultivation. A central composite design was applied to optimize the medium for Chlorella zofingiensis cultivation, which was considered to be a potential feedstock for biodiesel production. The optimal concentrations were 533.31 mg L-1 urea, 69.50 mg L-1 potassium dihydrogen phosphate, and 69.10 mg L-1 heptahydrate magnesium sulfate, and the corresponding biomass concentration of C. zofingiensis was 2.50 g L-1 after a 3-day culture.