This wire inductance calculator estimates the low-frequency self-inductance of a straight round conductor from its length and radius. Enter the dimensions above for the inductance in microhenries.
Formula
L (µH) = 0.2 × l × ( ln(2l ÷ r) − 0.75 )
Length l and radius r are in meters. The result is in microhenries.
Example
l = 1 m, r = 1 mm: L = 0.2 × 1 × (ln(2 ÷ 0.001) − 0.75) = 1.37 µH.
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Frequently Asked Questions
How do I calculate the inductance of a straight wire?
Use L = 0.2 times length times (ln(2 x length / radius) minus 0.75), with length and radius in meters and L in microhenries.
Does a straight wire have inductance?
Yes. Even a straight wire has self-inductance, small but important at high frequencies.
What affects wire inductance most?
Length increases it, while a larger radius slightly reduces it through the logarithm term.