Resonant Frequency (LC) Calculator

Work out resonant frequency (lc) instantly with clear inputs, formula shown and shareable results.

About Resonant Frequency (LC) Calculator

Resonance occurs where inductive and capacitive reactance are equal, giving f0 = 1/(2 pi sqrt(LC)). Because of the square root, quadrupling either component halves the frequency. Q is the reactance at resonance divided by the loss resistance, and bandwidth is f0/Q.

Formula

LC resonance

f0 = 1 / (2 pi sqrt(L x C)); Q = X0 / R; BW = f0 / Q

Worked example

With the default values below, Resonant Frequency (LC) Calculator returns Resonant frequency of 734.13. Change any input above and every figure here is recalculated in your browser.

Inputs used

Inductance: 100 µH
Capacitance: 470 pF
Series resistance: 2.2 Ω

Results

Resonant frequency: 734.13 kHz
Reactance at resonance: 461.27 Ω
Q factor: 209.67
3 dB bandwidth: 3.50 kHz

Step by step

1Values used
2LC resonance
3Resonant frequency= 734.13 kHz
4Reactance at resonance= 461.27 Ω
5Q factor= 209.67
63 dB bandwidth= 3.50 kHz

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

Frequently Asked Questions

Why is tuning a radio so sensitive?

Frequency varies as the inverse square root of capacitance, so a small variable capacitor sweeps a wide frequency range.

What limits Q in practice?

Winding resistance, core loss, dielectric loss and radiation. Air-cored coils with thick wire reach a few hundred; ceramic resonators reach thousands.