LC Resonance Calculator Formula

Understand the math behind the lc resonance calculator. Each variable explained with a worked example.

Formulas Used

Resonant Frequency

freq_hz = 1 / (2 * pi * sqrt(l_h * c_f))

Frequency (MHz)

freq_mhz = 1 / (2 * pi * sqrt(l_h * c_f)) / 1000000

Variables

VariableDescriptionDefault
inductance_uhInductance(µH)100
capacitance_pfCapacitance(pF)100
l_hDerived value= inductance_uh / 1000000calculated
c_fDerived value= capacitance_pf / 1000000000000calculated

How It Works

LC Resonant Frequency

f = 1 / (2 x pi x sqrt(L x C))

At resonance, inductive and capacitive reactances are equal and cancel, allowing maximum energy transfer.

Worked Example

100 uH and 100 pF.

inductance_uh = 100capacitance_pf = 100
  1. 01L = 100 uH = 0.0001 H
  2. 02C = 100 pF = 1e-10 F
  3. 03f = 1 / (2pi x sqrt(0.0001 x 1e-10))
  4. 04f = 1 / (2pi x sqrt(1e-14)) = 1 / (2pi x 1e-7)
  5. 05f = 1,591,549 Hz = 1.5915 MHz

Frequently Asked Questions

What happens at resonance?

XL = XC, impedance is minimized (series) or maximized (parallel), and energy oscillates between L and C.

What is this used for?

Radio tuning, oscillators, filters, impedance matching networks.

Does resistance affect resonant frequency?

Ideal resonant frequency is independent of resistance, but resistance affects bandwidth and Q factor.

Ready to run the numbers?

Open LC Resonance Calculator