Impedância RLC Série
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Z = √(R² + (X_L−X_C)²)
About this calculator
The Series RLC Impedance Calculator determines the total impedance of a circuit consisting of a resistor (R), inductor (L), and capacitor (C) connected in series. Impedance is the total opposition to alternating current flow, combining resistance and reactances. The formula used is Z = √(R² + (XL − XC)²), where XL = 2πfL is inductive reactance and XC = 1/(2πfC) is capacitive reactance. The result is given in ohms.
To use the calculator, enter the values of resistance, inductance, capacitance, and frequency. This calculation is useful in filter design, resonant circuits, and frequency response analysis. For example, engineers can size components to avoid unwanted resonance or to tune a circuit to a specific frequency.
Important precautions: ensure consistent units (ohms, henrys, farads, hertz). Frequency directly affects reactances; at very high frequencies, inductive reactance dominates, while at low frequencies, capacitive reactance prevails. Remember that impedance depends on frequency, so the calculation is only valid for the given frequency.
Frequently asked questions
What does negative impedance mean?
Impedance magnitude is always non-negative. The negative sign appears only in capacitive reactance (XC) in the formula, but the final Z is always positive.
Can I use this calculator for parallel circuits?
No. This calculator is specific for series RLC circuits. For parallel circuits, the impedance formula is different (Z = 1/√((1/R)² + (1/XL − 1/XC)²)).
What is the difference between impedance and resistance?
Resistance opposes direct current, while impedance also includes opposition from inductors and capacitors in alternating current. Impedance varies with frequency.
How does frequency affect impedance?
Increasing frequency increases inductive reactance (XL) and decreases capacitive reactance (XC). This can cause total impedance to increase or decrease, depending on which reactance dominates.
What happens when XL = XC?
When reactances are equal, resonance occurs. Total impedance is minimum and equal to resistance R. The circuit behaves purely resistive at that frequency.