Series RLC Impedance
For components connected in series, current is the same through all components
Impedance (Z)
0Ohms
Inductive Reactance (XL)
0Ohms
Capacitive Reactance (XC)
0Ohms
Phase Angle
0degrees
Parallel RLC Impedance
For components connected in parallel, voltage is the same across all components
Impedance (Z)
0Ohms
Inductive Reactance (XL)
0Ohms
Capacitive Reactance (XC)
0Ohms
Phase Angle
0degrees
Reactance Calculator
Calculate inductive and capacitive reactance separately
Inductive Reactance (XL)
0Ohms
Capacitive Reactance (XC)
0Ohms
XL = 2 * pi * f * L
XC = 1 / (2 * pi * f * C)
XC = 1 / (2 * pi * f * C)
Common Component Values
| Component | Typical Values | Common Applications |
|---|---|---|
| Resistor | 1 Ohm - 10 MOhm | Current limiting, voltage division, pull-up/down |
| Inductor | 1 uH - 100 mH | Power supplies, filters, transformers, RF circuits |
| Capacitor (Ceramic) | 1 pF - 10 uF | Decoupling, high-frequency filtering, timing |
| Capacitor (Electrolytic) | 1 uF - 10000 uF | Power supply smoothing, energy storage, coupling |
| AC Line Frequency | 50 Hz (EU), 60 Hz (US) | Power distribution, mains-powered equipment |
| Audio Frequency | 20 Hz - 20 kHz | Audio equipment, speakers, amplifiers |
| Radio Frequency | 3 kHz - 300 GHz | Wireless communication, broadcasting, radar |
Frequently Asked Questions
What is impedance?
Impedance (Z) is the total opposition to current flow in an AC circuit. It combines resistance (R) with reactance (X),
which varies with frequency. Unlike DC circuits where only resistance matters, AC circuits must account for how
inductors and capacitors store and release energy. Impedance is measured in Ohms and is expressed as a complex number
with magnitude and phase angle.
What is the difference between series and parallel RLC circuits?
In series RLC circuits, components are connected end-to-end, so the same current flows through all components.
The total impedance is Z = sqrt(R^2 + (XL - XC)^2). In parallel RLC circuits, components are connected across
the same voltage source, so voltage is the same across all components. The parallel impedance calculation uses
reciprocals: 1/Z = sqrt((1/R)^2 + (1/XL - 1/XC)^2).
What is reactance and how does it differ from resistance?
Reactance (X) is the opposition to current flow caused by inductors and capacitors in AC circuits. Unlike resistance,
which dissipates energy as heat, reactance stores energy temporarily and releases it back to the circuit. Inductive
reactance (XL) increases with frequency, while capacitive reactance (XC) decreases with frequency. This frequency
dependence is why AC circuit behavior changes with frequency.
What does phase angle mean?
Phase angle indicates the time shift between voltage and current in an AC circuit. A positive phase angle means
voltage leads current (inductive circuit), while a negative angle means current leads voltage (capacitive circuit).
At 0 degrees (purely resistive), voltage and current are in phase. This matters for power factor calculations and
understanding how real and reactive power interact in the circuit.
Why do inductors and capacitors have opposite effects?
Inductors resist changes in current by generating a back-EMF, making them oppose increases in current flow. This
causes current to lag behind voltage. Capacitors resist changes in voltage by storing charge, allowing current to
flow freely initially but then opposing further voltage changes. This causes current to lead voltage. These opposite
behaviors mean XL and XC subtract in impedance calculations, and at resonant frequency they cancel completely.
What happens at resonant frequency?
Resonant frequency occurs when XL = XC, meaning inductive and capacitive reactances cancel out. In a series RLC
circuit, impedance becomes purely resistive (minimum Z = R) and current reaches maximum. In parallel RLC circuits,
impedance becomes purely resistive (maximum Z) and current reaches minimum. This principle is used in tuning circuits,
filters, and oscillators. The resonant frequency is f = 1 / (2 * pi * sqrt(L * C)).
How do I convert between different unit prefixes?
Common conversions: Inductance - 1 mH = 0.001 H, 1 uH = 0.000001 H. Capacitance - 1 uF = 0.000001 F, 1 nF = 0.000000001 F,
1 pF = 0.000000000001 F. Frequency - 1 kHz = 1000 Hz, 1 MHz = 1000000 Hz. Always convert to base units (H, F, Hz)
before calculating impedance to avoid errors.
Can I use this calculator for DC circuits?
For DC circuits (frequency = 0 Hz), capacitors act as open circuits (infinite reactance) and inductors act as short
circuits (zero reactance). Only resistance matters in pure DC analysis. Use Ohm's Law calculator for DC circuits.
This impedance calculator is specifically designed for AC circuits where frequency creates reactive effects.
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are computed using standard formulas and should be verified for critical applications.
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Impedance Calculator FAQ
What is Impedance Calculator?
Impedance Calculator is a free engineering & physics tool that helps you Calculate AC circuit impedance, reactance, and phase angle for RLC circuits.
How do I use Impedance Calculator?
Enter your input values, review the calculated output, and adjust inputs until you reach the result you need. The result updates in your browser.
Is Impedance Calculator private?
Yes. Calculations run locally in your browser. Inputs are not uploaded to a server by default, and refreshing the page clears session data.
Does Impedance Calculator require an account or installation?
No. You can use this tool directly in your browser without sign-up or software installation.
How accurate are results from Impedance Calculator?
This tool applies standard formulas or deterministic processing logic for estimates. For medical, legal, tax, or investment decisions, verify with a qualified professional.
Can I save or share outputs from Impedance Calculator?
You can bookmark this page and copy outputs manually. Results are not persisted in your account and are typically not embedded in the URL.