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Wire Inductance Calculator
Estimate the self-inductance and inductive reactance of a straight isolated round wire from length, diameter, and frequency.
Input Parameters
Results
Use the result as a first-pass parasitic inductance estimate.
Equations Used
Straight Wire Approximation:
L ≈ 2 × 10^-7 × l × [ln(2l/r) - 0.75] H
Reactance:
XL = 2πfL
Where:
l = wire length, r = wire radius, f = frequency
Frequently Asked Questions (FAQ)
Q1: When is wire inductance important?
It matters in fast switching loops, RF wiring, grounding leads, current sense leads, and high di/dt paths.
Q2: Does wire shape affect inductance?
Yes. Loops, bends, nearby conductors, and return paths strongly affect inductance.
Q3: Is this for an isolated wire?
Yes. The formula assumes a straight isolated round conductor.
Q4: How can I reduce wire inductance?
Shorten the wire, increase conductor width, reduce loop area, and keep the return path close.
Q5: Does skin effect change inductance?
Skin effect mainly changes AC resistance, but high-frequency current distribution can also change effective impedance.
Q6: Can this model PCB traces?
For PCB traces over a plane, use a PCB trace inductance or transmission-line model instead.
