Techniques are described herein that are capable of using an efficiency indicator for increasing efficiency of a wireless power transfer. A wireless power transfer system includes features that allow the system to be deployed in public spaces such as airports or in commercial establishments such as restaurants or hotels to allow a user to recharge one or more portable electronic devices while away from home. The system may provide an efficiency indicator to a portable electronic device that specifies a recommended position of the portable electronic device. The recommended position may correspond to an efficiency with respect to the wireless power transfer that is greater than an efficiency with respect to the wireless power transfer that corresponds to a position of the portable electronic device. The portable electronic device may generate a sensory signal that indicates the recommended position with reference to the position of the portable electronic device.