LC Resonance Calculator
Calculate resonant frequency, inductance, or capacitance for an ideal LC tank circuit. Enter any two values to solve for the third.
What an LC Circuit Calculator Does
An LC circuit calculator helps you quickly compute resonance behavior in a circuit made of an inductor (L) and a capacitor (C). In ideal conditions, these components exchange energy back and forth: the capacitor stores electric energy, and the inductor stores magnetic energy. This oscillation happens at a natural resonant frequency.
Whether you are building an RF filter, tuning circuit, oscillator, or matching network, the key question is usually the same: what values of L and C give me the target frequency? This tool answers that in one step.
Core Resonance Formula
Resonant frequency:
f = 1 / (2π√(LC))
- f = frequency in hertz (Hz)
- L = inductance in henries (H)
- C = capacitance in farads (F)
This calculator also rearranges the formula to solve for L or C when frequency is known.
How to Use This LC Circuit Calculator
1) Pick a calculation mode
Select whether you want to find resonant frequency, inductance, or capacitance.
2) Enter two known values
Use practical units like µH, nF, kHz, or MHz. The calculator converts everything to SI units internally.
3) Click Calculate
You will see:
- The solved value in SI and engineering notation
- Angular frequency (ω0 = 2πf)
- Oscillation period (T = 1/f)
- Characteristic impedance estimate Z0 = √(L/C) for ideal tank analysis
Example Use Cases
RF tuning stage
Suppose you want to tune near 1 MHz and already have a 250 µH inductor. The calculator can solve the required capacitance in pF or nF range, making it easier to pick a standard capacitor or variable trimmer.
Filter prototyping
When testing a narrowband band-pass section, you can estimate resonance quickly and then account for real-world losses (coil resistance, ESR, and PCB parasitics).
Educational labs
This is useful for students studying resonance and energy transfer between electric and magnetic fields.
Important Practical Notes
- Real components are not ideal. Coil resistance and capacitor ESR shift and damp resonance.
- Tolerance matters. A 5% capacitor can move frequency significantly at high Q.
- Parasitics matter at high frequency. Lead length, traces, and self-resonance can dominate behavior.
- Simulation and measurement are still essential. Use this as a design-start tool, then validate with SPICE and lab instruments.
Quick FAQ
Is this for series or parallel LC circuits?
The resonance equation is the same for ideal LC values. Real impedance behavior differs between series and parallel configurations, especially around bandwidth and peak response.
Why did my measured frequency differ from the calculated result?
Likely due to component tolerance, inductor DC resistance, capacitor ESR, loading effects, and parasitic capacitance/inductance.
Can I use scientific notation in inputs?
Yes. Inputs such as 1e-6 are accepted by most browsers.
Bottom Line
This LC circuit calculator gives you a fast and reliable starting point for resonance design. Use it to choose initial values, then refine with realistic models and measurements for final performance.