LC Resonant Frequency Calculator
This LC resonance calculator finds the resonant frequency of an LC circuit from the inductance and capacitance, using f = 1 / (2π √(LC)). Enter both and the LC resonance calculator returns the resonant frequency in MHz, kHz, and Hz. It works as an LC tank circuit calculator for tuned and oscillator circuits.
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What the LC resonance calculator shows
An inductor and a capacitor together form a circuit that resonates at one frequency, swapping energy back and forth. This LC resonance calculator finds that resonant frequency from the inductance and capacitance. Whether you use it as an LC tank circuit calculator, an LC tuned circuit calculator, or an LC oscillator frequency calculator, it gives the frequency the circuit naturally rings at.
How to calculate resonant frequency of LC circuit
To calculate the resonant frequency of an LC circuit, the LC resonance calculator uses:
L is the inductance in henries and C is the capacitance in farads. Resonance is where the inductive and capacitive reactances are equal and cancel, leaving only resistance. Because f depends on the product LC under a square root, quadrupling either component halves the frequency.
LC circuit resonant frequency calculator example
A 100 µH inductor with a 100 pF capacitor. The LC circuit resonant frequency calculator gives:
So the circuit resonates near 1.59 MHz, in the AM radio band. Change either value and the LC resonance calculator updates the frequency at once.
How to use the LC resonance calculator
Enter the inductance in microhenries and the capacitance in picofarads, then the LC resonance calculator returns the resonant frequency in MHz, kHz, and Hz. These units suit radio frequency work; scale them for audio circuits. To calculate the resonant frequency of an LC circuit you need only the two component values, since the resonance depends on their product.
Reading the LC resonance calculator result
The resonant frequency is where the circuit responds most strongly, used to tune a radio to a station or to set an oscillator. A parallel LC tank blocks that frequency, while a series LC passes it, so the same resonance serves as either a filter or a tuner depending on the arrangement. To move the frequency, change the capacitor for fine tuning and the inductor for a bigger jump. The LC resonance calculator gives the ideal frequency; real coils and capacitors shift it a little.
When to use the LC tank circuit calculator
- Tuning a radio stage with the LC tank circuit calculator
- Setting an oscillator with an LC oscillator frequency calculator
- Designing a filter with an LC tuned circuit calculator
- Finding the resonance of a given L and C
Common LC resonance calculator mistakes
- Wrong component units. A microhenry and a picofarad are tiny; convert carefully before the formula.
- Ignoring stray effects. Stray capacitance and coil resistance shift the real resonance from the ideal.
- Confusing series and parallel. A series LC passes the resonant frequency; a parallel tank blocks it.
Tips for LC circuits
- Tune finely with the capacitor and coarsely with the inductor.
- Keep the units straight: henries and farads give hertz.
- Allow for stray capacitance at high frequencies.
The LC circuit resonance calculator formula
The LC circuit resonance calculator formula, f = 1 / (2π√(LC)), comes from the point where the two reactances match. The inductive reactance rises with frequency while the capacitive reactance falls, and at exactly one frequency they are equal and opposite, so they cancel and the circuit presents only its small resistance. That balance point is the resonant frequency, and it depends on the product of L and C under a square root, which is why a small inductor with a small capacitor resonates high, in the megahertz, while a large coil and capacitor resonate low, in the kilohertz. An lc calculator frequency result of a few megahertz, from a 100 µH and 100 pF pair, lands right in the AM broadcast band.
LC oscillator frequency calculator and tank circuits
An LC oscillator frequency calculator uses the same formula, because an LC oscillator is a tank circuit kept swinging by a little energy added each cycle to replace losses. In a parallel LC tank the inductor and capacitor pass energy back and forth, the magnetic field of the coil charging the capacitor and the capacitor discharging back through the coil, at the resonant frequency. That is the same stored energy an inductor and a capacitor hold, now trading places many times a second. A series LC resonance calculator gives the same frequency for a series tank, which passes rather than blocks that frequency, so the arrangement decides whether the resonance filters a signal out or lets it through.
LC tuned circuit calculator values
Resonant frequency for several L and C pairs, from the LC tuned circuit calculator:
| Inductance | Capacitance | Resonant frequency |
|---|---|---|
| 100 µH | 100 pF | 1.59 MHz |
| 100 µH | 1000 pF | 503 kHz |
| 10 µH | 100 pF | 5.03 MHz |
| 1 mH | 10 nF | 50.3 kHz |
LC Resonant Frequency Calculator FAQ
What is the LC resonant frequency formula?
The formula is f = 1 / (2 pi root(L C)). The LC resonance calculator applies it, with L in henries and C in farads, and shows the result in MHz, kHz, and Hz.
What happens at resonance?
The inductive and capacitive reactances are equal and cancel. A series LC passes the resonant frequency, while a parallel LC tank blocks it.
How do I change the resonant frequency?
Change the capacitor for fine tuning and the inductor for a larger shift. Because f depends on the product LC, quadrupling either halves the frequency.
Does a real circuit match the calculator?
Closely. Stray capacitance, coil resistance, and component tolerance shift the real resonance a little from the ideal LC resonance calculator value.