Light scattering models were adapted from prior works to study the impact of pore size, pore distribution, and porosity on the transmission of polycrystalline lead halide perovskite ceramics. First, the scattering efficiency (Qsca) was calculated for a range of pore sizes constrained by the NanoCT derived pore size distribution (~35-635 nm) for the l=0.989 mm MAPbBr3 ceramic (see Figure and main text Figure ). Specifically, Qsca was calculated for pore diameters ranging from dp=35 nm to dp=635 nm in 10 nm steps. Pores were treated as spherical inclusions with refractive indices of n=1 surrounded by a host medium with refractive indices taken from ellipsometry measurements on MAPbBr3 single crystals. Qsca was calculated via Mie theory using an established numerical approach (BHMIE scattering code, see Figure ). After calculating Qsca, scattering cross-sections (Csca) for the entire pore distribution were calculated by multiplying the scattering efficiency by the projected area (𝐴 = 𝜋𝑑 /4) of the spherical pore such that (𝐶 = 𝑄 × 𝐴 , see Figure ). From there, the theoretical transmission of the sample was estimated via Beer-Lambert extinction law :