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RLC Impedance Calculator.

Calculate series-RLC impedance magnitude and phase at a frequency.

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01

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Results update as you type.

Impedance: 153.19848 Ω

Impedance

0.000000Ω
Reactance: -152.871758 Ω

Reactance

0.000000Ω
Phase: -86.257369 °

Phase

0.000000°

Results update automatically as you type.

Use Cases

Design and analysis of RLC filters

Engineers use impedance calculations to design resonant circuits, filters, and impedance matching networks. This calculator helps determine the impedance at a specific frequency for tuning.

Example: Design a series RLC band-pass filter with R=50Ω, L=10mH, C=100nF, and check impedance at 5kHz.

Educational tool for AC circuit analysis

Students and educators can quickly verify impedance calculations for series RLC circuits, reinforcing concepts of reactance and phase relationships.

Example: Verify the impedance of a circuit with R=100Ω, L=0.1H, C=10μF at 60Hz.

Frequently Asked Questions

What does the RLC Impedance Calculator compute?
It computes the total impedance magnitude and phase angle of a series RLC circuit at a given frequency. You input resistance (Ω), inductance (H), capacitance (F), and frequency (Hz), and it returns the impedance magnitude in ohms and the phase angle in degrees.
How is the impedance magnitude calculated?
The magnitude is calculated using the formula |Z| = sqrt(R^2 + (XL - XC)^2), where XL = 2πfL and XC = 1/(2πfC). The phase angle is arctan((XL - XC)/R).
What units should I use for the inputs?
Use ohms (Ω) for resistance, henries (H) for inductance, farads (F) for capacitance, and hertz (Hz) for frequency. The calculator assumes these SI units and does not convert between prefixes.

Tips & Common Mistakes

Tips

  • Ensure all values are in base SI units: ohms, henries, farads, and hertz. Convert millihenries (mH) to henries (H) by dividing by 1000, and microfarads (μF) to farads (F) by dividing by 1,000,000.
  • At resonance (XL = XC), the impedance is purely resistive and the phase angle is zero. Use the calculator to find the resonant frequency by adjusting frequency until phase is 0°.
  • For frequencies far from resonance, the impedance magnitude is dominated by the larger reactance. Check if the circuit is inductive (positive phase) or capacitive (negative phase).
  • Double-check your frequency value: if you are using kHz, multiply by 1000 to get Hz.

Common Mistakes to Avoid

  • Forgetting to convert units: entering inductance in mH or capacitance in μF without converting to H and F will produce incorrect results.
  • Using the wrong formula: mixing up inductive reactance (XL = 2πfL) and capacitive reactance (XC = 1/(2πfC)) can lead to sign errors in phase.
  • Assuming the phase angle is always positive: the phase can be negative when capacitive reactance exceeds inductive reactance.

Last updated: August 13, 2026