Alternating Current
Parallel RLC Impedance Calculator
Parallel RLC Impedance helps you find impedance magnitude from resistance, frequency, inductance, and capacitance. The page keeps the arithmetic visible so you can check the result against the original measurements.
Enter values for Impedance magnitude
Enter ratings or measurements that describe one scenario.
Formula used on this page
For this worksheet, the governing relationship is |Z| = 1 ÷ √(G² + (BC − BL)²). The participating entries are Resistance, Frequency, Inductance, and Capacitance.
The initial scenario returns 271.06 Ω. Re-enter field data before using the answer in a design or comparison.
Calculate ideal parallel RLC impedance. When impedance magnitude affects the next decision, use Series RLC Impedance Calculator.
Input notes
Record frequency, waveform, phase arrangement, and whether voltage is line or phase. Write down whether each entry is measured, rated, assumed, or calculated.
At least one field has a positive lower bound because it appears in a denominator. Convert units once, retain the original reading, and verify the converted magnitude.
- Resistance
- Default example: 500 Ω. Enter resistance in Ω.
- Frequency
- Default example: 1000 Hz. Enter frequency in Hz.
- Inductance
- Default example: 0.05 H. Enter inductance in H.
- Capacitance
- Default example: 1 µF. Enter capacitance in µF.
Interpreting the answer
Interpret Impedance magnitude on the same basis used for the source values. Compare it with impedance, phase, waveform, and equipment ratings.
A result without its source conditions is difficult to compare or audit.
Sensitivity check
Change Resistance from 500 Ω to 600 Ω as the sole changed variable. The two results are 271.06 Ω to 284.11 Ω.
Keep both cases when the changed input represents genuine uncertainty.
Where this estimate can fail
Each component must share the same two nodes.
The equation does not include frequency-dependent loss, parasitics, and waveform distortion. Resolve material omissions before selecting a standard size or rating.
Keep distorted-waveform measurements separate from sine-wave assumptions.
Common questions before using the result
What happens when a denominator is zero?
Use a measured positive value for Resistance, Frequency, Inductance, and Capacitance; zero cannot stand in for missing data.
Should I use measured or nameplate values?
Choose entries that describe the same case. Use RMS values unless an input explicitly requests peak amplitude.
What assumptions affect Impedance magnitude?
Each component must share the same two nodes. A broader review should include harmonics, phase imbalance, saturation, and nonsinusoidal current.
What explains a gap between calculated and observed impedance magnitude?
Differences can come from frequency-dependent loss, parasitics, and waveform distortion, measurement uncertainty, or values taken under different conditions.
Can I change several inputs at once?
Change one uncertain entry at a time and preserve the baseline. Use RMS values unless an input explicitly requests peak amplitude.
Can I select equipment from this number alone?
The calculator does not approve equipment or supply an unexplained margin. Compare against the applicable line-to-line or line-to-neutral limit.