The curve of solid fat content (SFC) is a fundamental but significant physical characteristic of fat, which markedly affects the texture and sense of food. A bivariate Gompertz model with temperature and saturated fatty acids (SFAs) as variables was used in this study to fit the SFC curve of enzymatically interesterified vegetable oil from palm olein (PO) and palm stearin (ST), to determine the ideal proportion of plant-based fat substrate. The fitting result (R² = 0.99) showed that this model had respectable predictive power. When the PO/ST ratio was 83:17, the SFC curve of the prepared plant-based margarine was close to that of butter, as calculated using the acquired SFC curve fitting formula. Bread characteristics and sensory analysis showed that the acceptance level of the bread made with this formulation was similar to that of natural animal fats. The results demonstrated that using the Gompertz function to build a simulated fit of SFC curves for enzymatically interesterified fat blends is a beneficial tool for optimising margarine formulation.