Systems and methods for setting an operating frequency for wireless charging systems. The wireless charging system comprises a transmitter circuit configured to generate a magnetic field in response to a current having an operating frequency and driving the transmitter circuit, and a receiver circuit configured to receive power via the magnetic field. The transmitter circuit and the receiver circuit are separated by an offset distance that contributes to a level of detuning between the transmitter and receiver circuits. To reduce a level of detuning, a level of coupling between the transmitter and receiver circuits is determined based upon a measured current or voltage value associated with the receiver circuit. From the determined level of coupling, the offset distance can be estimated. The offset distance may be used to determine a desired operating frequency for reducing the level of detuning between the transmitter circuit and the receiver circuit.