Wire Inductance
Any conductor has inductance. This tool gives the low-frequency self-inductance of the three common geometries: a straight round wire, a single circular loop, and a two-wire line (the loop inductance of the pair). Enter the wire diameter and the relevant dimension; add a frequency for the reactance.
Equations & Parameters ▸
straight wire: \(L = \dfrac{\mu_0 \ell}{2\pi}\left(\ln\dfrac{2\ell}{r} - \tfrac{3}{4}\right)\)
circular loop: \(L = \mu_0 R\left(\ln\dfrac{8R}{r} - 2\right)\)
two-wire line: \(L = \dfrac{\mu_0}{\pi}\ln\dfrac{s}{r}\,\ell\)
circular loop: \(L = \mu_0 R\left(\ln\dfrac{8R}{r} - 2\right)\)
two-wire line: \(L = \dfrac{\mu_0}{\pi}\ln\dfrac{s}{r}\,\ell\)
| d, r | Wire diameter and radius (r = d/2), mm. |
| ℓ | Wire / line length (mm), for the straight-wire and two-wire cases. |
| D | Loop diameter (mm) for the circular loop (R = D/2). |
| s | Centre-to-centre conductor spacing (mm) for the two-wire line. |
| L | Self-inductance (external, low-frequency; skin effect removes the internal part at RF). |
References: F. W. Grover, Inductance Calculations, Dover, 2004. · C. R. Paul, Inductance: Loop and Partial, Wiley, 2010.
Inputs
Conductor shape
mm
Conductor Ømm
Wire / linemm
Loop onlymm
Two-wire onlyMHz
For XₗResults
Inductance
Inductance L—
Per unit length—
At frequency
Reactance XL—
Diagram