Please enter all required numeric values.
Formulas & Mathematical Logic
Series to Parallel: Rp = Rs × (1 + Xs² / Rs²)
Series to Parallel: Xp = Xs × (1 + Rs² / Xs²)
Parallel to Series: Rs = (Rp × Xp²) / (Rp² + Xp²)
Parallel to Series: Xs = (Xp × Rp²) / (Rp² + Xp²)
Capacitance reactance: Xc = -1 / (2 × π × f × C)
Inductance reactance: XL = 2 × π × f × L
About This Calculator
Convert series and parallel impedance without getting lost in complex-number math.
This CalcBoy calculator helps you move between equivalent series and parallel circuit models for resistance, reactance, capacitance and inductance at a selected frequency.
In AC circuits, the same real-world component can often be described in two useful ways: as a series impedance model or as a parallel impedance model. A capacitor with loss, an inductor with winding resistance, or a resonant RF network may look different on paper, but at one operating frequency these models can represent the same electrical behavior.
Best UseRF matching networks, tuned circuits, filters, audio crossovers and impedance transformation.
Supported InputsResistance, reactance, capacitance, inductance and frequency with practical engineering units.
Helpful ForComparing ESR models, inductor losses, simulation values and measured impedance data.
Design ReminderEquivalent conversion is frequency-specific, so always use the real operating frequency.
The calculator is especially useful when a datasheet, simulation tool, LCR meter or RF design method gives a value in one form, but your circuit calculation needs the other form. For example, an impedance analyzer may report a parallel model while your matching network uses a series model, or a filter equation may require a parallel resistance even though the component loss is measured as series resistance.
Quick idea: series impedance is often easier to understand as resistance plus reactance in the signal path, while parallel impedance is useful when leakage, damping or shunt loss must be modeled across a circuit node.
How to use this calculator
Choose whether you want Series to Parallel or Parallel to Series conversion.
Enter the resistance value and select the correct ohm multiplier.
Select reactance, capacitance or inductance as the reactive component type.
Enter the operating frequency so capacitance and inductance can be converted correctly.
Press Calculate and compare series resistance, parallel resistance, series reactance and parallel reactance.
For practical circuit design, treat the result as an equivalent value at the selected frequency, not as a universal value for every frequency. Real components also include parasitic capacitance, winding resistance, lead inductance, dielectric loss, temperature drift and tolerance. These effects matter more at high frequency, so RF impedance conversion and filter design should always be checked with actual component data or measurement.
Why does frequency matter?
Capacitive reactance and inductive reactance change with frequency, so capacitance and inductance conversions need the operating frequency to produce meaningful impedance values.
Can I use this for RF matching?
Yes. It is useful for RF matching networks, resonant circuits and filter analysis, but final RF designs should also consider Q factor, PCB layout, parasitics and measurement accuracy.
Is this the same as simple resistor series-parallel conversion?
No. This calculator works with impedance, so it includes both resistance and reactance. That makes it suitable for AC circuits, capacitors, inductors and frequency-dependent networks.