Entering two of the three values for capacitance, inductance, or frequency will find the remaining value.

Resonance in a series or parallel LC circuit occurs at the frequency where the reactance of the inductor and capacitor are the same.Parallel LC circuits, commonly called a tank circuit, are frequently used in bandpass filters.Due to the phase difference between the impedance of the capacitor and inductor, the impedance of the parallel combination is 0 when their reactances are equal.Following similar reasoning, series LC circuits finds use in bandstop filters.

The equations used to find at which frequency an LC combination resonates is: