Last updated: 2026-06-16

Inductors in Series and Parallel

Two inductors can be wired end to end (series) or side by side across the same two nodes (parallel), and each connection gives a different equivalent inductance. This calculator takes two inductances $L_1$ and $L_2$ and a choice of connection, and returns the single equivalent inductance $L_{eq}$.

Formula

Inductors combine the same way resistors do: they add in series and combine reciprocally in parallel. This is the opposite of how capacitors behave. Both formulas assume the inductors are not magnetically coupled.

Worked example

Two $10\ \text{mH}$ inductors.

In series the total is larger than either inductor; in parallel it is smaller than the smaller one. For two equal inductors, parallel gives exactly half the value.

Series vs parallel at a glance

Why it matters

Combining inductors lets you reach a value that no single standard part provides, or share current and voltage stress across several components. Series connection raises inductance and is common in filters and chokes; parallel connection lowers it and can increase the current-handling capacity. Remember that these results hold only when the coils do not share magnetic flux — if they are physically close, the mutual inductance between them changes the total, adding to it or subtracting from it depending on how the windings are oriented.