This paper presents dynamic modeling for cross-spring pivots, based on the Beam Constraint Model (BCM) and Lagrangian method. The effect of vertical force is included in this model. The first natural frequency of the cross-spring pivot under vertical force is derived. The effects on the first natural frequency imposed by manufacturing errors are studied. The model predictions of the first natural frequency were compared with FEA results for two configurations of cross-spring pivots. The model predictions are within 2% of the FEA results for all cases.