Basic Electrical Laws calculator
Impedance Calculator
At 50 + j30 ohms, this impedance calculator returns 58.31 ohms magnitude and 30.96 degrees; at 10 ohms, 50 mH, and 100 uF on 60 Hz, the series RLC screen returns about 12.61 ohms and 9.52 A from 120V. It is a one-frequency lumped-element screen, not a harmonic, fault-current, or field-measurement substitute.
Updated July 10, 2026
A 50 + j30 ohm impedance has a magnitude of about 58.31 ohms and a phase angle of about 30.96 degrees. A 10 ohm, 50 mH, 100 uF series circuit at 60 Hz screens at about 12.61 ohms and 9.52A from 120V.
XL = 2πfL | XC = 1 ÷ (2πfC) | Series Z = R + j(XL − XC)
Choose series RLC, parallel RLC, complex impedance, or series resonance below and enter the values at one frequency
Example Calculations
More examples. Open to review 1 additional calculation example.
How to Use
How to use the impedance calculator
- Choose RLC impedance, complex impedance, or series resonance.
- For an RLC impedance check, choose series or parallel and enter the component values at one frequency.
- For a complex impedance check, enter the real and imaginary parts directly in ohms.
- Use the optional applied voltage only when you also want current and power from the resolved impedance.
- Read the magnitude, angle, and equivalent real/reactive parts together.
Core relationships used here
Inductive reactance: XL = 2πfL
Capacitive reactance: XC = 1 ÷ (2πfC)
Series impedance: Z = R + j(XL − XC)
Parallel admittance: Y = G + jB, then Z = 1 ÷ Y
Magnitude: |Z| = √(R² + X²)
Series resonance: f0 = 1 ÷ (2π√LC)
What this page returns
| Output | Meaning | Typical use |
|---|---|---|
| Equivalent resistance and reactance | Real and imaginary parts of the resolved impedance | Comparing inductive versus capacitive behavior at one frequency |
| Impedance magnitude and angle | Overall opposition to current and the phase shift | Current calculations, phasor checks, and quick AC circuit review |
| Current and power from voltage | Only when you enter applied voltage in RLC mode | Checking one operating point at one frequency |
| Resonant frequency, Q, and bandwidth | Simple series-resonance screen | Bench and filter checks before a fuller network review |
Scope notes
- This page is a lumped-element sinusoidal screen at one frequency.
- It does not replace a harmonic study, fault-current model, or field measurement.
- Parallel RLC results come from admittance first, then conversion back to equivalent impedance.
- The resonance mode is a series-resonance screen, not a full filter-design package.
Example 1: a 10 ohm, 50 mH, 100 uF series circuit at 60 Hz screens at about 12.61 ohms magnitude and about -37.51 degrees because XC is greater than XL at that frequency.
Example 2: a complex impedance of 50 + j30 ohms screens at about 58.31 ohms magnitude and about 30.96 degrees.
Example 3: a 50 mH and 100 uF series pair screens at about 71.18 Hz of resonance. Add resistance when you want Q and bandwidth instead of only frequency.
Use the RC Circuit Calculator when the real question is time constant or cutoff frequency, the Power Factor Correction Calculator when the real task is capacitor kVAR sizing, and the Short Circuit Calculator when the job is available fault current rather than one-frequency circuit impedance.
Common Applications
More applications. Open to review 2 additional use cases.
Frequently Asked Questions
What is the difference between resistance, reactance, and impedance?
Resistance is the real part that dissipates power. Reactance is the imaginary part created by inductance or capacitance. Impedance combines both into one complex quantity, Z = R + jX.
Why is the parallel RLC result not just 1 divided by net reactance?
Because a parallel network must be solved in admittance first. The conductance and susceptance branches add, and only then is the equivalent impedance found from Z = 1/Y.
What does a negative phase angle mean?
It means the resolved impedance is capacitive at that frequency. A positive angle indicates inductive behavior.
Can I use this page for harmonic-filter or system-resonance design?
Only as a first screen. Real harmonic or system-resonance work needs source impedance, network detail, and often field measurements or a fuller simulation model.
Does the resonance mode cover all kinds of resonance?
No. It is a simple series-resonance screen based on the entered L, C, and optional resistance. It does not model distributed or multi-branch resonance behavior.
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