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PCB Trace Inductance Calculator
Estimate the parasitic inductance of a PCB trace over a reference plane using transmission-line impedance and propagation velocity.
Input Parameters
Results
Use this for traces with a reasonably continuous reference plane.
Equations Used
Transmission-Line Relation:
L per meter = Z0 / v
Propagation Velocity:
v = c / sqrt(εeff)
Total Inductance:
Ltotal = L per meter × trace length
Capacitance per Meter:
C per meter = 1 / (Z0 × v)
Frequently Asked Questions (FAQ)
Q1: What does PCB trace inductance affect?
It affects switching overshoot, ringing, EMI, current loops, and high-speed signal integrity.
Q2: Why use a reference plane model?
A trace over a plane has a controlled return path, so inductance is tied to transmission-line impedance and velocity.
Q3: Is this the same as isolated wire inductance?
No. A trace over a plane usually has lower loop inductance than an isolated wire because of the nearby return current.
Q4: Does the return path matter?
Yes. Slots, poor ground return, or distant return paths can increase loop inductance dramatically.
Q5: Can this be used for power loops?
It is useful for first-pass estimates, but switching power loops should be checked with layout extraction or measurement.
Q6: How do I reduce trace inductance?
Use shorter traces, wider copper, close return planes, and compact current loops.
