A wireless power transmitting device for foreign object detection based on coil current sensing, comprising: a first transmitter coil ; a coil current sensing circuit coupled to the first transmitter coil , wherein the coil current sensing circuit is configured to measure a peak coil current value and the resonant frequency at the first transmitter coil ; and a controller configured to: determine, via the coil current sensing circuit , a coil current value corresponding to a first coil current that passes through the first transmitter coil , wherein the coil current is determined by calculating a root mean square of the coil current based on the peak coil current value and the resonant frequency; compute a transmitter power loss based on the coil current value; compute a transmission power loss based on the transmitter power loss computed based on the coil current and a received power received at a receiver coil of a receiving device , wherein the received power has been received at the transmitting device by communication from the receiving device ; and determine, during wireless power transfer from the wireless power transmitting device to a wireless power receiving device , an existence of a foreign object in vicinity of the first transmitter coil when a change in the computed transmission power loss meets a threshold condition. a first transmitter coil ; a coil current sensing circuit coupled to the first transmitter coil , wherein the coil current sensing circuit is configured to measure a peak coil current value and the resonant frequency at the first transmitter coil ; and a controller configured to: determine, via the coil current sensing circuit , a coil current value corresponding to a first coil current that passes through the first transmitter coil , wherein the coil current is determined by calculating a root mean square of the coil current based on the peak coil current value and the resonant frequency; compute a transmitter power loss based on the coil current value; compute a transmission power loss based on the transmitter power loss computed based on the coil current and a received power received at a receiver coil of a receiving device , wherein the received power has been received at the transmitting device by communication from the receiving device ; and determine, during wireless power transfer from the wireless power transmitting device to a wireless power receiving device , an existence of a foreign object in vicinity of the first transmitter coil when a change in the computed transmission power loss meets a threshold condition. determine, via the coil current sensing circuit , a coil current value corresponding to a first coil current that passes through the first transmitter coil , wherein the coil current is determined by calculating a root mean square of the coil current based on the peak coil current value and the resonant frequency; compute a transmitter power loss based on the coil current value; compute a transmission power loss based on the transmitter power loss computed based on the coil current and a received power received at a receiver coil of a receiving device , wherein the received power has been received at the transmitting device by communication from the receiving device ; and determine, during wireless power transfer from the wireless power transmitting device to a wireless power receiving device , an existence of a foreign object in vicinity of the first transmitter coil when a change in the computed transmission power loss meets a threshold condition. <EOS>