Inductor Energy Calculator

Energy Stored in an Inductor

When current flows through an inductor, energy is stored in its magnetic field. This calculator finds that stored energy from inductance and current. It is useful for power electronics, flyback converters, and discharge safety analysis.

Formula

$$E = \frac{1}{2} L I^2$$

$E$ is energy in joules, $L$ is inductance in henries, and $I$ is current in amperes. Convert microhenries to henries and milliamperes to amperes before applying the formula.

Practical Notes

Stored energy rises with the square of current, so even small inductors can release significant energy at high current. When an inductive circuit opens, that energy can produce voltage spikes unless a snubber or freewheeling path is provided.

Frequently Asked Questions

What units should I use?

Enter inductance in microhenries (μH) and current in milliamperes (mA). The calculator converts to SI units internally and reports energy in joules or convenient submultiples.

Why does energy depend on I squared?

Magnetic energy density is proportional to B², and B is proportional to current in a linear inductor. Integrating over the coil volume gives the ½LI² relationship.

Does this include core losses?

No. This is ideal stored magnetic energy. Real cores also dissipate energy through hysteresis and eddy currents.

What happens when current stops suddenly?

The inductor tries to maintain current, which can create a large voltage spike. Use diodes, TVS devices, or snubbers in switching circuits.

Is this the same as capacitor energy?

Capacitors store energy as ½CV² in an electric field. Inductors store energy as ½LI² in a magnetic field. Both scale with the square of their driving quantity.

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Energy Stored in an Inductor

Formula

Practical Notes

Frequently Asked Questions

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