Spiral Coil Inductance Calculator

Spiral Coil Inductance Calculator

Estimate the inductance using: $$ L = \frac{\mu_0 \, N^2 \, d_{\text{avg}}}{2} \left[\ln\!\left(\frac{2.46}{\rho}\right) + 0.2\,\rho^2\right] $$

* Enter the number of turns \(N\), inner diameter \(d_{\text{in}}\) (mm), and outer diameter \(d_{\text{out}}\) (mm). Diameters are converted to meters; the result is in nanohenries (nH).

Step 1: Enter Parameters

e.g., 5 turns

e.g., 2 mm

e.g., 10 mm

Formula: $$ L = \frac{\mu_0 \, N^2 \, d_{\text{avg}}}{2} \left[\ln\!\left(\frac{2.46}{\rho}\right) + 0.2\,\rho^2\right] $$
where \( d_{\text{avg}} = \frac{d_{\text{in}} + d_{\text{out}}}{2} \) and \( \rho = \frac{d_{\text{out}} – d_{\text{in}}}{d_{\text{out}} + d_{\text{in}}} \).