This paper reports methods for measuring the spring constant and modeling the deflection of piezoelectric devices. Because this method uses the equivalent electric circuit of the piezoelectric device and deflection with respect to input voltage, it is a noncontact measurement method. Measurements of the spring constant from the equivalent circuit method and force versus deflection measurements are within 3.3% of each other. An equivalent electrical circuit of the piezoelectric device is also used to provide a model of the relationship between frequency and deflection according to input voltage. Input voltage and power with respect to driving frequency are modeled for a constant mechanical deformation. This model gives an estimation of the required input electrical power to piezoelectric devices for many applications. In order to verify the models, experiments are conducted and the models and experimental results show very good agreement.