# Inductor Energy Calculator

URL: https://speedycalculator.com/calculators/physics/inductor-energy/
Last updated: 2026-10-30

> The inductor energy calculator finds the energy stored in the magnetic field of an inductor carrying a current.

## Inputs

- Inductance L (mH, µH, nH, H)
- Current I (A, mA, µA, kA)

## Results

- Stored energy
- Flux linkage

## Formula

```
E = ½·L·I²
```

## Explanation

An inductor stores energy in its magnetic field. Interrupt the current suddenly and that energy produces a high voltage spike – how ignition coils make sparks, and why relays need flyback diodes.

### How to use the Inductor Energy Calculator

- **Inductance L**
- **Current I**
- Every result field is editable: type into **Stored energy** and **Current I** plus every other field update to match.

Results update as you type, every field has its own unit menu, and everything is calculated in your browser.

### How it works

Enter the inductance and current, or type an energy into the result to find the current.

### Inputs explained

FieldWhat to enterInductance LUnits: mH, µH, nH, HCurrent IUnits: A, mA, µA, kA

### What each result means

- **Stored energy** = 0.5×[Inductance L]×[Current I]^2
- **Flux linkage** = [Inductance L]×[Current I]

### Example values

How the main result changes when **Current I** changes and everything else stays at the example values above:

Current I (A)Stored energy (mJ)151.511.252202.531.25345480

## Worked example

Inputs — Inductance L: 10 mH; Current I: 2 A.

Results — **Stored energy = 20 mJ**; Flux linkage = 0.02 Wb.

## Key terms

- **Henry**: Unit of inductance, V·s/A.

## FAQ

**Where is the energy stored?**
In the magnetic field, mostly in the core gap.

**Why do relays need diodes?**
Collapsing coil current would create a damaging voltage spike.

**How does energy scale with current?**
With its square.

**What limits the energy?**
Core saturation and wire heating.


## Sources

- [OpenStax – University Physics Volume 2](https://openstax.org/details/books/university-physics-volume-2)
- [HyperPhysics (Georgia State University)](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html)