LC Circuit Calculator | Resonant Frequency & Q

Calculate LC and RLC resonant frequency, impedance, Q factor, and bandwidth

Includes component tolerance analysis, E-series value snap, and sweep summary...

When Should You Use This Calculator?

Designing resonant tanks and tuned filters from target frequency
Evaluating impedance and phase behavior for RLC networks
Estimating resonance drift from component tolerance windows
Snapping computed L/C to practical E-series component values
Running sweep-style impedance analysis with optional parasitics

How to Use This Calculator

Choose circuit type and target calculation (f, L, C, or Z).
Enter known component values with units.
Expand Component Tolerance Analysis to set L/C tolerance and optional E-series snapping.
Expand Frequency Sweep & Parasitics to add ESR and inspect the impedance sweep summary.

Key Features:

One unified screen — solve for frequency, inductance, capacitance, or impedance
Resonance, impedance, reactance, Q factor, and bandwidth
Tolerance frequency range and E-series standard-value snap
Impedance sweep summary with optional parasitic ESR analysis

Formula

Resonant Frequency: f = 1 / (2π√(LC)); Series Impedance: Z = R + j(XL - XC)

Design mode adds tolerance range and standard-value snapping.
Analysis mode summarizes sweep behavior around the operating region.

Frequently Asked Questions

What is the difference between simple, design, and analysis modes?

Simple mode solves the core LC/RLC equations quickly. Design mode adds tolerance range and standard-value snap support. Analysis mode adds sweep summary and optional parasitic ESR handling for more realistic behavior checks.

Why use tolerance and sweep features?

Tolerance range helps estimate resonance drift from real component variation. Sweep summary helps you see where impedance is lowest/highest around an operating region, useful for tuning filters and resonant networks.

What is Q factor and why does it matter?

Q factor (Quality Factor) measures how underdamped a resonant circuit is. A high Q means the circuit resonates sharply with low energy loss — useful for narrow-band filters. A low Q means a broader, more lossy response. Q = f_resonant / Bandwidth. This calculator computes Q automatically from your L, C, and R values.

How do I calculate the resonant frequency of an LC circuit?

Resonant frequency is f = 1 / (2π√(LC)), where L is inductance in henries and C is capacitance in farads. For a 100 µH inductor and a 100 nF capacitor, resonance is about 50.3 kHz. Enter any two of frequency, L, or C above and the calculator solves for the third, with optional standard-value snapping in Design mode.

Can I export my LC Resonant Circuit Calculator calculations?

Yes. In guest mode you can export your calculations to JSON. Signing in adds PDF and CSV export. Click the export button to download your results — useful for record-keeping, sharing, or importing into other tools.

Does this calculator save my history?

Yes. Your calculation history is saved automatically. As a guest you can keep up to 50 calculations per workspace on your device. Sign in for free to keep up to 100 per workspace and access them from any device.

Is this calculator free to use?

Yes. The LC Resonant Circuit Calculator is free to use with no sign-up required. A free account adds more calculation history, multiple workspaces, and access to your saved data from any device.

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