Inductors In Series Calculator

Work out inductors in series instantly with clear inputs, formula shown and shareable results.

About Inductors In Series Calculator

Inductors in series add, but if their fields interact the mutual inductance adds twice: Ltotal = L1 + L2 + 2M with M = k x sqrt(L1 x L2). The sign depends on winding orientation, so aiding fields increase inductance and opposing fields reduce it.

Formula

Series inductance

Ltotal = L1 + L2 + 2M, M = k sqrt(L1 L2); k = 0 for uncoupled coils

Worked example

With the default values below, Inductors In Series Calculator returns Total inductance of 349.66. Change any input above and every figure here is recalculated in your browser.

Inputs used

Inductor 1: 100 µH
Inductor 2: 220 µH
Mutual coupling coefficient: 0.1 k
Current: 2 A

Results

Total inductance: 349.66 µH
Mutual inductance: 14.83 µH
Sum ignoring coupling: 320.00 µH
Energy stored: 699.33 µJ

Step by step

1Values used
2Series inductance
3Total inductance= 349.66 µH
4Mutual inductance= 14.83 µH
5Sum ignoring coupling= 320.00 µH
6Energy stored= 699.33 µJ

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

Frequently Asked Questions

When is coupling zero?

When the coils are far apart, at right angles, or shielded. Toroids couple very little because their flux is contained.

What if the fields oppose?

Then M is subtracted twice, and with perfect coupling of equal coils the total inductance falls to zero — the principle behind a non-inductive winding.