We present the design and analysis of a new type of MEMS inertia switch with a tunable threshold, which can passively sense angular acceleration. The designs have a big proof mass for inducing rotation due to the angular impacts and also flexible cantilever beams to tune the acceleration threshold. The proposed designs were simulated using COMSOL Multiphysics, analytically modeled, and numerically integrated using MATLAB. The results showed that the acceleration can be tuned from 0 rad/s$^2$ to 65,000 rad/s$^2$ based on the used electrostatic voltage. The designs experience less than 10% overshot for shock durations higher than 20 ms. The rise time was less than 10 ms for all designs when the applied shock duration was less than 30 ms. The designs’ tunabilities were studied and characteristic angular acceleration versus tuning voltage graphs were developed for each design. The tuning voltage varied between the designs where the maximum pull-in voltage was 179 V in Design 2 and the minimum pull-in voltage was 59 V in Design 4.