This study introduces a practice-oriented methodology for calibrating partial safety factors for material properties. The proposed approach integrates sensitivity analysis with the Star Design with Central Point (SDCP) method to: (i) identify the most influential random variables affecting the seismic response of unreinforced masonry structures; and (ii) calibrate the associated safety factors based on their quantified influence, using a reduced set of numerical simulations. The methodology is applied at both panel and wall scales, accounting for different modelling strategies, including discrete and finite element approaches. This allows for an assessment of how in-plane slenderness, structural typology, and modelling choices impact the calibration process. Furthermore, the study compares the proposed method with full-probabilistic analyses and conventional confidence factor-based approaches. Results highlight the capability of the proposed approach to provide accurate safety estimates while significantly reducing computational demand, thus making it a viable option for practical seismic assessment applications.