The frequency at which an inductor-capacitor (LC) circuit naturally oscillates, a foundational result used throughout radio and filter design.
How it works
The resonant frequency is the reciprocal of 2π times the square root of the inductance multiplied by the capacitance.
What this does not include
This does not include circuit resistance or damping effects — this calculator specifically finds the ideal, undamped resonant frequency of the LC pair.
How to use this calculator
- Enter the inductance in henries and the capacitance in farads.
A worked example
A 0.001 H inductor with a 1 µF capacitor: resonant frequency = 1/(2π√(LC)) = 5,032.9212 Hz.
A 0.01 H inductor with a 0.1 µF capacitor: resonant frequency is also 5,032.9212 Hz — a different L and C combination can land on the identical resonant frequency.
What the variables mean
| Variable | Meaning |
|---|---|
| Inductance | Inductor value, in henries |
| Capacitance | Capacitor value, in farads |
Edge cases worth knowing
Multiple L-C pairs can produce the same resonant frequency, as the second example shows directly — it’s the product LC that matters, not the individual values.
Zero inductance makes the frequency infinite, which has no physical meaning — the calculator declines to show a result for that case.
Frequently asked questions
What happens if I double the inductance and halve the capacitance?
The resonant frequency stays exactly the same — it depends only on the product of L and C, not on either one individually.
Where is LC resonance used practically?
Radio tuners, filters, and oscillator circuits all rely on an LC pair’s resonant frequency to select or generate a specific frequency.
Why does a smaller capacitance raise the frequency?
Because the resonant frequency is inversely proportional to the square root of capacitance — a smaller C means a higher frequency, all else equal.
