Inductive Reactance & RL Impedance Calculator
Enter frequency and inductance to compute inductive reactance. Add resistance to get total series RL impedance magnitude and phase angle.
What this inductance impedance calculator does
This tool calculates the inductive reactance of a coil and the total impedance of a simple series RL circuit. If you work with AC circuits, motor windings, filters, chokes, or transformers, this gives you a quick way to estimate how strongly an inductor resists alternating current.
Key concepts in plain language
Inductance (L)
Inductance is a component's ability to oppose changes in current. It is measured in henries (H), commonly millihenries (mH) or microhenries (µH).
Inductive reactance (XL)
Reactance is frequency-dependent resistance to AC. For an inductor:
- f = frequency in hertz (Hz)
- L = inductance in henries (H)
- XL = reactance in ohms (Ω)
Total impedance in a series RL circuit
If a resistor and inductor are in series, the impedance magnitude is:
The phase angle between voltage and current is:
How to use the calculator
- Enter frequency and choose Hz, kHz, or MHz.
- Enter inductance and choose H, mH, or µH.
- Optionally enter resistance for a series RL impedance calculation.
- Click Calculate to view reactance, impedance magnitude, and phase angle.
Practical examples
Example 1: Power frequency choke
For 60 Hz and 100 mH: XL ≈ 37.7 Ω. If R = 10 Ω, then |Z| ≈ 39.0 Ω and current lags voltage by about 75°.
Example 2: Higher frequency behavior
With the same inductor at 1 kHz, reactance rises dramatically. This is why inductors are useful for blocking high-frequency noise while passing lower-frequency current.
Common mistakes to avoid
- Using mH or µH without converting to H.
- Mixing up Hz and kHz.
- Assuming inductive reactance is constant (it changes with frequency).
- Forgetting that real components include parasitics and tolerance.
Engineering notes
This calculator models an ideal inductor and a simple series RL network. Real inductors include winding resistance, core losses, saturation effects, and parasitic capacitance. For precision RF or power electronics design, use measured impedance data or a full SPICE model.
Quick FAQ
Is reactance the same as resistance?
No. Resistance dissipates power as heat; reactance stores and releases energy in electric or magnetic fields.
Why does inductor impedance increase with frequency?
Because changing current induces a larger opposing voltage at higher rates of change, which corresponds to higher frequency.
Can I use this for capacitor impedance too?
Not directly. Capacitive reactance uses a different formula: XC = 1/(2πfC).