Inductors in Series Calculator
Calculate equivalent inductance and magnetic energy for three series-connected inductors.
Series Inductor Network
Enter three uncoupled inductances and the common series current.
About Inductors in Series
For ideal uncoupled inductors connected in series, equivalent inductance is the sum of the individual inductances. The same current flows through every component because there is only one current path. Each inductor develops a voltage proportional to its own inductance and the rate of current change, while the individual voltages add to the source voltage. Three coils of 10, 20, and 30 millihenries therefore behave like one 60-millihenry inductor in the ideal model.
The calculator also determines total magnetic energy from E = 1/2 L total I squared. Because every series inductor carries the same current, summing each coil's individual energy gives exactly the same result as using equivalent inductance. This provides a useful check when analyzing energy storage in filters, electromagnets, converter stages, and pulsed circuits. Current has a squared influence, so a modest increase in current can create a much larger increase in stored energy.
Series connections are often used when a required inductance is not available as one standard component, or when designers want to distribute voltage and heat across several coils. Total winding resistance also adds in series, although this ideal calculator does not include resistance. In an AC circuit, the total inductive reactance can be found by applying XL = 2 pi f L to the equivalent inductance. The series current then depends on that reactance plus all other circuit impedance.
The simple sum assumes no mutual magnetic coupling. Coils mounted close together or wound on a shared core can aid or oppose one another depending on orientation. Their equivalent inductance then includes mutual-inductance terms and may be higher or lower than the arithmetic sum. Component tolerances, core saturation, parasitic capacitance, and winding resistance also affect real behavior. Verify voltage ratings and insulation because the applied voltage divides among coils according to impedance, not necessarily equally.
Enter inductance values in henries and the common instantaneous or peak current in amperes. Use peak current to calculate maximum stored energy. The result applies to an ideal linear magnetic system, so consult each component's saturation-current curve when evaluating hardware. If a winding saturates, its inductance falls and the calculated energy distribution no longer remains accurate. Within these assumptions, adding inductances offers a direct, transparent estimate for education and early circuit design.
Examples
| Inputs | Calculated results |
|---|---|
| 10, 20, 30 mH at 2 A | 60 mH total and 0.12 J |
| Three 0.5 H coils at 3 A | 1.5 H total and 6.75 J |
| 0.1, 0.2, 0.7 H at 1 A | 1 H total and 0.5 J |
How to Use This Calculator
- Enter all three inductance values in henries.
- Enter the current that flows through the series path.
- Select Calculate to add the inductances and find stored energy.
- Compare the current with each inductor's saturation rating.
Frequently Asked Questions
How do series inductors combine?
Ideal uncoupled series inductances add directly. A 1 H coil and a 2 H coil therefore produce 3 H total.
Is current equal through every series inductor?
Yes, one current flows through every element in a single series path. Voltage can differ across the inductors according to their impedance.
How is total stored energy calculated?
Use one-half times equivalent inductance times current squared. This equals the sum of the energy stored by each individual coil.
Does magnetic coupling change total inductance?
Yes. Coupled coils include mutual-inductance terms whose sign depends on winding orientation, so simple addition may not apply.
Do winding resistances add too?
Yes, the series winding resistances add just like ordinary resistors. This calculator focuses on ideal inductance and magnetic energy rather than loss.