Biofuels are extensively used as primary fuel in cookstoves by the rural masses in India. About 70% of the population resides in the rural area, out of which 70% are entirely dependent on biofuels for their energy requirements. The traditional cookstoves are poorly designed causing inefficient burning. Hence, the efforts are needed to improve the quality of these cookstoves concerning of design and efficiency. The present work overcomes the difficulty of designing the two-pot biomass cookstove by presenting a simple mathematical approach to evaluate the thermal performance using the heat and mass transfer equations. The model predicts the heat interaction between the stove body and pots, combustion temperatures in different zones, the thermal efficiency and excess air ratio for different geometrical parameters of the stove. The model values are validated with the experimental results and found to be in close agreement. The findings of the model are likely to change the future cookstove modeling and design approach.