LC resonant frequency calculator
Used in tuned circuits, oscillators and filters. Enter L and C and pick their units.
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How to use it
- Enter inductance, inductance unit, capacitance and capacitance unit.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
f = 1 ÷ (2π × √(L × C)), angular frequency ω = 1 ÷ √(L × C), with L in henries and C in farads.
Example
Inputs: Inductance = 1, Inductance unit = millihenry (mH), Capacitance = 1, Capacitance unit = microfarad (µF). Result: Resonant frequency: 5,032.921 Hz; Short form: 5.0329 kHz; Angular frequency: 31,622.777 rad/s.
Limits and caveats
- Assumes an ideal inductor and capacitor; coil resistance and stray capacitance shift the real frequency, especially at high frequencies.
- The formula applies to ideal series and parallel resonant circuits alike.
Questions about this tool
What is the resonant frequency of 1 mH and 1 µF?
About 5.03 kHz.
What happens at resonance?
The inductor and capacitor reactances are equal and cancel. A series circuit has minimum impedance; a parallel one has maximum.
How do I double the frequency?
Divide L × C by 4, for example by cutting the capacitance to a quarter with the same coil.