Abstract: The British Pendulum Tester (BPT) is an internationally widely used device for pavement skid resistance measurement. However, the conversion model between its British Pendulum Number (BPN) and the coefficient of friction (COF) exhibits significant engineering deviations, because conventional models neglect variations in contact pressure and the heterogeneity of equipment parameters. To address this issue, this study first calibrated the slider force–deflection characteristics through force measurement tests using an electronic balance, and then established a finite element model of the entire BPT testing process to reveal the intrinsic relationship between contact pressure and COF. Based on this, a generalized BPN–COF conversion model was proposed. The simulation results indicate that when the COF exceeds 0.4, the contact pressure decays nonlinearly with increasing COF, causing the prediction error of traditional models to increase progressively. Experimental verification demonstrates that the slider force–deflection characteristics of the BPT device affect the characteristic parameters of the generalized conversion model, and after calibration, the generalized model reduces the COF prediction error to within 3.6%. These findings provide a theoretical model foundation and an equipment calibration scheme for enhancing the reliability of BPT test results and device compatibility.