Physics

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LC Filter Calculator.

Calculate ideal LC resonant frequency.

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01

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Results update as you type.

Resonant frequency: 5,032.92121 Hz

Resonant frequency

0.000000Hz
Angular frequency: 31,622.776602 rad/s

Angular frequency

0.000000rad/s

Results update automatically as you type.

Use Cases

Designing LC filters for signal processing

Determine the resonant frequency of an LC filter to ensure it passes or blocks the desired frequency band in audio, RF, or communication circuits.

Example: Set L=0.001 H and C=0.000001 F to find the resonant frequency for a low-pass filter.

Tuning oscillator circuits

Calculate the resonant frequency of an LC tank circuit used in oscillators, such as in radio transmitters or receivers, to achieve the desired oscillation frequency.

Example: For L=0.0001 H and C=0.0000001 F, the resonant frequency is about 1.59 MHz.

Frequently Asked Questions

What is the resonant frequency of an LC circuit?
The resonant frequency is the frequency at which the inductive and capacitive reactances cancel each other out, causing the circuit to oscillate naturally. It is calculated using the formula f = 1 / (2π√(LC)), where L is inductance in henries and C is capacitance in farads.
How do I use this LC filter calculator?
Simply enter the inductance value in henries (H) and the capacitance value in farads (F) into the respective fields. The calculator will compute the ideal resonant frequency in hertz (Hz) using the standard formula.
What units should I use for inductance and capacitance?
The calculator expects inductance in henries (H) and capacitance in farads (F). If you have values in other units like millihenries or microfarads, convert them to base units before entering.

Tips & Common Mistakes

Tips

  • Ensure inductance and capacitance are in base units (henries and farads) before entering them to get accurate results.
  • For quick conversions: 1 mH = 0.001 H, 1 µH = 0.000001 H, 1 µF = 0.000001 F, 1 nF = 0.000000001 F.
  • The calculator provides the ideal resonant frequency; real-world components have tolerances that may shift the actual frequency slightly.
  • Use the result to verify that your LC filter's resonant frequency aligns with your circuit's operating frequency.

Common Mistakes to Avoid

  • Forgetting to convert units to henries and farads, leading to incorrect frequency calculations.
  • Using the formula incorrectly, such as omitting the factor 2π or the square root, which yields wrong results.
  • Assuming the resonant frequency is the cutoff frequency for all LC filters; it is the frequency of maximum response, not always the -3dB point.

Last updated: August 13, 2026