Ceramic capacitors offer reliable and dense energy storage in power conversion applications. However, to effectively incorporate these devices in a design, it is important to have an accurate model of losses for the conditions under which the devices will be used. Small signal loss parameters at low bias voltage are frequently provided by the manufacturer, but the correlation between these data and losses exhibited under realistic large signal excitation has not been explored in detail. This work aims to provide a method for measuring capacitor losses under realistic operating conditions, using a calorimetric approach to provide an accurate measurement of losses under large signal excitation. Specifically this work will investigate the effect of high voltage bias and varying AC excitation on losses. This work concludes with a proposed loss model which encompasses operation of large signal excitation over varying frequencies and DC biases.