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Inductor Energy Storage Calculator

Calculate the energy stored in an inductor's magnetic field, and its flux linkage, from inductance and current.

Energy stored
5 J
Flux linkage
1 Wb

How it works

An inductor stores energy in the magnetic field built up around it as current flows through, following the identity W = ½ × L × I², where L is inductance in henries and I is current in amps — the magnetic-field counterpart to a capacitor's electric-field energy E = ½ × C × V². It comes from integrating the power delivered as current ramps from zero to I, since the voltage across an inductor is V = L × (dI/dt). Verified via web search against HyperPhysics's and Electrical Academia's own 'Energy Stored in an Inductor' references.

Flux linkage ψ = L × I (in weber-turns) is reported alongside energy the same way this site's Capacitor Energy calculator reports charge Q = C × V — it's the inductor's analog of a capacitor's stored charge, and the two equivalent forms W = ½ × ψ × I = ψ² ÷ (2L) fall out of substituting ψ back in. Inductance and current are left as plain inputs with no metric/imperial toggle, since henries and amps are already abstract electrical SI units with nothing to convert.

FAQ

How is this different from the Capacitor Energy calculator?

A capacitor stores energy in an electric field (E = ½CV², scaling with voltage squared); an inductor stores energy in a magnetic field (W = ½LI², scaling with current squared). They're the electrical and magnetic counterparts of the same energy-storage idea, but for physically different components with different governing equations — a charged capacitor holds its energy with no current flowing, while an inductor needs current flowing to hold any.

What happens to that energy if the current is suddenly interrupted?

An inductor resists sudden changes in current, so abruptly opening a circuit carrying current through an inductor forces that stored energy somewhere very fast — commonly seen as a voltage spike or arc across the switch contacts. This is exactly why real inductive loads (relay coils, motor windings) are usually paired with a flyback diode or snubber to give that energy a safe path to dissipate.

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