<p>While the inner profile of a blast furnace (BF) follows general standardization, its specific design remains largely experience-based. BF process modeling and optimization offer a systematic and cost-effective approach to studying the effects of key variables, including material properties, BF geometry, and operational conditions, providing valuable insights for BF design and control. In this work, a 3D BF process model was employed to investigate the design rules for BF geometry in the 1000 to 5000 m³ volume range. First, under fixed operating conditions, the optimal BF geometry for each volume was identified by minimizing total energy consumption. The results show that the method employed in this study can quantitatively replicate well-established industrial trends related to BF volume. Secondly, an analysis of transport phenomena within a furnace provided a rationale for these geometric trends. Lastly, it is shown that the optimum BF profile is also affected by the preset geometric constraints, even under the same operating conditions. Therefore, customized BF design may be required to better align with varying production needs.</p>