<p>Design of piezoelectric energy harvesters (PEHs) with high power output requires piezoceramics with a large transduction coefficient (d₃₃ × g₃₃). However, since the dielectric permittivity ε_r typically increases with the piezoelectric charge coefficient d₃₃, it leads to a reduction in the voltage coefficient g₃₃, making it challenging to simultaneously achieve a high d₃₃ × g₃₃ in PEH materials. In this study (BCZT) ceramics were prepared with varying grain sizes to modify the influence of ε_r and improve the d_ij and g_ij coefficients. Sol–gel derived BCZT powders were sintered at 1400 ℃ with varying peak dwell time (1&#xa0;h to 12&#xa0;h) resulting in grain sizes from approximately 10&#xa0;µm to 30&#xa0;µm. BCZT ceramics containing grain size larger than ~ 16&#xa0;µm showed better ferroelectric and piezoelectric properties. Sharp dielectric transition and a high permittivity of ~ 17000 were observed for larger grain sized BCZT ceramics. A notable remnant polarization (P_r) of 12 µC/cm² along with a low coercive field (E_c) of 0.14&#xa0;kV/mm was obtained from the BCZT sample with a grain size ~ 24&#xa0;µm. Grain size larger than 20&#xa0;µm had shown higher piezoelectric coefficients (d₃₃, d₃₃*, g₃₃) and electromechanical coefficient (k_p). A high transduction coefficient d₃₃ × g₃₃ = 15.1 × 10⁻¹² m²/N, with high figure of merit FOM = 13.7 × 10⁻¹⁰ m²/N were obtained in this study. These values are mostly significant for PEH applications, as they directly correlate with the power generation efficiency of the material under external mechanical stimulus. The ability to achieve such high transduction coefficients and FOM in lead-free BCZT ceramics highlights its strong potential for use in next-generation PEHs and in similar such energy harvesting devices. The insights gained on this grain size study of this lead-free system provide a solid foundation for further material optimization tailored specifically for high-performance and environmentally friendly energy harvesting systems.</p>