Inductor Energy Calculator
This Inductor Energy Calculator determines magnetic energy stored from inductance and current, or reverse-solves the inductance or current required for a target energy.
It supports switching-converter analysis, choke and relay design, transient protection, pulse circuits, and component stress checks where magnetic energy must be stored or safely released.
The ideal equation assumes constant inductance. Verify saturation, core loss, winding resistance, temperature, current rating, and discharge paths in practical hardware.
Engineering tool
Inductor Energy Calculator
Calculate stored magnetic energy, or solve the inductance or current required for a target energy.
Effective inductance at the circuit operating point.
Instantaneous inductor current used for the energy calculation.
Stored energy (E)
5 mJ
E = ½ × L × I²
Result console
- Stored energy (E)
- 5mJ
- Inductance (L)
- 10mH
- Current (I)
- 1A
Stored energy depends on inductance and the square of current. Check saturation current and safe energy handling in the real circuit.
Magnetic Energy in an Inductor
Current through the winding establishes a magnetic field. The field stores energy until current changes or a discharge path releases it.
Formula reference
Inductor Energy Formulas
Inductor energy is proportional to inductance and to the square of current. Current therefore has a strong effect on stored energy and component stress.
Stored energy: E = ½ × L × I²Required inductance: L = 2E / I²Required current: I = √(2E / L)Variable definitions
- E
- Stored magnetic energy in joules (J)
- L
- Inductance in henries (H)
- I
- Instantaneous current in amperes (A)
How to Use This Calculator
- Select whether to calculate energy, inductance, or current.
- Enter the two known values and choose their engineering units.
- Select Calculate to apply the ideal magnetic-energy equation.
- Compare the result with saturation, current rating, losses, and safe discharge requirements.
Worked Example
10 mH Inductor at 1 A
L = 10 mH = 0.01 H
I = 1 A
E = ½ × 0.01 × 1²
E = 0.005 J = 5 mJ
Engineering Notes
Current has a squared effect
Inductor energy increases with the square of current, so doubling current ideally stores four times as much energy.
Saturation limits usable energy
Core saturation reduces effective inductance and sets a practical limit on predictable magnetic energy storage.
Energy matters across hardware
Stored energy is important in switching converters, chokes, relays, solenoids, and transient circuits.
Real components include losses
Core material, winding resistance, tolerance, current waveform, and temperature affect real inductor behavior.
Interrupted current creates voltage
Stored energy can produce a high voltage spike when current is interrupted, requiring a flyback diode, clamp, snubber, or other safe path.
Common Mistakes
- Using mH, mA, or mJ values without converting them to SI base units.
- Using average current when peak inductor current determines maximum energy.
- Assuming inductance remains constant beyond the saturation region.
- Ignoring winding, core, and switching losses during energy transfer.
- Interrupting current without a safe clamp or recirculation path.
Support reference
FAQ
How much energy is stored in an inductor?
Stored energy depends on inductance and current according to E = ½LI². The result is expressed in joules and represents ideal magnetic-field energy at that instantaneous current.
How do you calculate inductor energy?
Convert inductance to henries and current to amperes, then calculate one-half times inductance times current squared. For example, 10 mH at 1 A stores 5 mJ.
Why does current affect inductor energy so strongly?
Current is squared in the energy equation. Doubling current ideally increases stored energy by four times, provided inductance remains constant and the core does not saturate.
What happens to stored energy when an inductor current is interrupted?
The inductor generates voltage to oppose the rapid current change. Without a controlled discharge path, stored energy can create a damaging voltage spike or arc.
Is inductor energy the same as power?
No. Energy is stored work measured in joules, while power is the rate of energy transfer measured in watts. Power relates to how quickly energy is stored, released, or dissipated.
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Browse the Inductors calculator category or review related material in the Engineering Reference Center.
This calculator provides ideal magnetic energy values for engineering reference. Verify saturation, incremental inductance, winding and core loss, current rating, temperature, insulation, transient voltage, and the energy discharge path before production use.