Calculates the energy stored in the magnetic field of a current-carrying inductor.
How it works
Half the inductance is multiplied by the square of the current flowing through it.
What this does not include
This does not include the energy stored in a capacitor’s electric field — for that different form of energy storage, use this site’s capacitor energy calculator instead.
How to use this calculator
- Enter the inductance and the current flowing through the inductor.
A worked example
A 0.5 H inductor carrying 2 A: energy = ½LI² = 0.5 × 0.5 × 2² = 1 J.
A 0.1 H inductor carrying 5 A: energy = 1.25 J.
What the variables mean
| Variable | Meaning |
|---|---|
| Inductance | The inductor’s storage capacity, in henries |
| Current | Current flowing through the inductor, in amps |
Edge cases worth knowing
Stored energy scales with the square of current, not linearly — doubling the current quadruples the stored energy, the same squared relationship seen in capacitor energy and kinetic energy.
A negative inductance has no physical meaning — inductance is always positive, so the calculator declines to show a result for a negative input.
Frequently asked questions
Why is current squared in this formula?
The same reason voltage is squared for capacitor energy — the stored magnetic field strength scales with current, so energy scales with its square.
What’s a real-world use for inductor energy storage?
Switching power supplies and inductive energy-storage systems rely on briefly storing energy in an inductor’s magnetic field during each switching cycle.
Why does an inductor resist sudden current changes?
Because a changing current changes the stored magnetic energy, and the inductor opposes that change — this is the same physical property this formula’s energy value comes from.
