LC Resonant Frequency Calculator
Calculate the resonant frequency of an LC tank circuit from inductance and capacitance, or solve for the required inductance or capacitance for a target resonance. Includes angular frequency, period, and reactance at resonance.
LC resonant frequency formula
An LC circuit resonates when the inductive reactance and capacitive reactance have equal magnitude. In an ideal circuit, the resonant frequency depends only on inductance and capacitance.
Worked example
Real circuits also include winding resistance, ESR, parasitic capacitance, layout inductance, component tolerance, and load resistance. These affect Q, bandwidth, and the measured resonant point.
Common uses
LC resonance appears in RF tank circuits, oscillators, impedance matching networks, filters, wireless power circuits, snubbers, and EMI troubleshooting. For high-frequency designs, parasitic capacitance and self-resonant frequency of the inductor become important.
Common questions
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Use f = 1 ÷ (2π√LC), where L is inductance in henries and C is capacitance in farads.
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The inductive reactance and capacitive reactance are equal in magnitude. Energy transfers between the magnetic field of the inductor and the electric field of the capacitor.
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Yes. Enter the target frequency and capacitance, and the calculator solves L = 1 ÷ ((2πf)²C).
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Yes. Enter the target frequency and inductance, and the calculator solves C = 1 ÷ ((2πf)²L).
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Real components have tolerance, ESR, winding resistance, parasitic capacitance, and layout effects. These can shift the measured resonant frequency and reduce Q.
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The ideal resonant frequency formula is the same for simple series and parallel LC networks, but impedance behavior differs at resonance.
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Angular frequency is ω = 2πf and is measured in radians per second.
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At resonance, XL = XC in magnitude. This calculator displays that reactance value from 2πfL.