Resonant Frequency

How to use this calculator

Resonance is the frequency at which an inductor and capacitor "balance" each other. For an LC network the resonant frequency is f₀ = 1 / (2π√(LC)). This general tool reports f₀ plus the inductive and capacitive reactances at that point, which are equal in magnitude (X_L = X_C) — the defining condition of resonance.

What it means in a real circuit

Resonance is the principle behind tuning, filtering, and oscillation. A resonant circuit stores energy sloshing back and forth between the magnetic field of L and the electric field of C, producing a strong response at f₀ and a weak one elsewhere. Engineers use it to select a radio channel, build a clock, or reject an interference frequency. The Q factor (not shown here — see Bandwidth) determines how sharp that peak is.