This study investigated the impact of pouch cell design on energy density, both volumetric and gravimetric, through the development of accurate 3D models of small-format (<5 Ah) pouch cells. Various configurations were analysed, considering material properties and extrapolating expected electrochemical performance from studies on Prussian white cathodes in coin and pouch cells. This approach allowed for a rapid assessment of several performance-influencing factors, including the number of layers in the pouch cell, cathode thickness, active material percentage, and electrolyte volume. The highest calculated energy density of small-format pouch cells was shown to be 282 Wh kg⁻¹ and 454 Wh L⁻¹, achieved in a 3 Ah, 20-layer pouch cell. The calculations were validated using sodium-ion anode-free pouch cells utilising a Prussian white cathode in single- and few-layer format pouch cells (<0.1 Ah) cycled under a low external pressure (~200 kPa).