Systems and methods pertaining to wireless power transfer are disclosed. Specifically, disclosed herein are calibration procedures that incorporate transmission of a reference power charge from a wireless power charger to permit determination of an optimized receiver circuitry configuration in one or more wirelessly chargeable devices. The result of the calibration procedures may then be used by the wireless charger to assign various frequencies to several wirelessly chargeable devices so as to optimally transfer a steady state power charge at one or more frequencies to the wirelessly chargeable devices.