Some demonstrative embodiments include apparatuses, systems and/or methods of wireless power transfer. For example, an apparatus may include a wireless power controller to communicate between a Wireless Power Receiver (WPR) and a Wireless Power Transmitter (WPT) an indication of a requested amount of power to be provided from the WPT to the WPR via a wireless power signal, said indication is in the form of a load modulation event within a predefined time interval, said load modulation event comprises a change in a level of a magnetic field of said wireless power signal, a duration of said load modulation event is based on the requested amount of power to be provided from the WPT to the WPR.