RLC Resonant Frequency Calculator
Compute the resonant frequency and quality factor of a series RLC circuit, and see how inductive and capacitive reactance cross at resonance.
H
F
Ω
Frequency where inductive and capacitive reactance cancel
- 1
L × C product
0.001 × 0.0000001 = 0 - 2
√(L × C)
√(0) = 0.00001 - 3
Resonant frequency f₀ = 1 ÷ (2π√LC)
1 ÷ (2π × 0.00001) = 15,915.49
How does this calculator work?
A series RLC circuit resonates at f₀ = 1/(2π√(LC)), where inductive and capacitive reactance cancel and impedance is minimal. Only L and C set this frequency. Adding resistance R yields the quality factor Q = (1/R)√(L/C), which controls how sharp the resonance is and its bandwidth f₀/Q.
Formula
How this is calculated
Enter the inductance L in henries and the capacitance C in farads. The resonant frequency is f₀ = 1 / (2π·√(L·C)), the frequency at which the inductive reactance XL = 2π·f·L exactly equals the capacitive reactance XC = 1 / (2π·f·C). At that point the two reactances cancel and the series impedance is purely resistive (minimum), so the circuit responds most strongly.
Resistance R is optional. When you provide it, the quality factor Q = (1/R)·√(L/C) measures how sharp the resonance is: higher Q means a narrower, taller response. The −3 dB bandwidth follows as f₀/Q, and √(L/C) is the characteristic impedance, equal to the common value of XL and XC at resonance. The angular resonant frequency is ω₀ = 2π·f₀.
The plot shows XL rising linearly with frequency and XC falling as 1/f over a band around f₀; their intersection marks resonance. Assumptions: ideal linear, lossless reactive components and a series topology. L and C must be positive; if either is zero or blank the formula is undefined. Use consistent SI units (H, F, Ω) — for example 1 µF = 1e-6 F and 1 mH = 1e-3 H.
Frequently asked questions
For an ideal series RLC circuit the resonant frequency depends only on L and C through f₀ = 1/(2π√(LC)). Resistance affects the sharpness (Q) and bandwidth of the resonance, not its center frequency.
Q describes how selective the resonance is. A high Q (small R relative to √(L/C)) gives a narrow, sharp peak and low energy loss per cycle; a low Q gives a broad, damped response with bandwidth f₀/Q.
Use SI units: henries for L, farads for C, ohms for R. Convert prefixes first — 10 µF is 0.00001 F, 47 mH is 0.047 H. You can use scientific notation such as 1e-7 for 100 nF.
Also known as
TG we-Calculate Editorial Team. (2026). RLC Resonant Frequency Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/rlc-resonant-frequency-calculator
TG we-Calculate Editorial Team. "RLC Resonant Frequency Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/rlc-resonant-frequency-calculator.
TG we-Calculate Editorial Team, "RLC Resonant Frequency Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/rlc-resonant-frequency-calculator
@misc{wecalculate_rlc_resonant_frequency_calculator, title = {RLC Resonant Frequency Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/rlc-resonant-frequency-calculator}}, year = {2026}, note = {TG we-Calculate} }
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