Inductor Energy

Enter inductance and current to compute stored energy. Includes unit conversions and Show Work.

How to Use

  1. Enter any two values (Energy, Inductance, Current) to solve the third.
  2. Select units (µH, mH, A, mA, mJ, etc.).
  3. Use “Solve For” to force a specific output if desired.
  4. Open “Show Work” to see base-unit formulas and steps.
Energy Storage View
Energy increases with L and with the square of current (I²).
E
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L
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I
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Risk: —
Stored energy
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Visual is relative (normalized) to help compare “what-if” changes.
Inputs & Settings
Enter any two values. Energy is computed using base units (H, A, J).
Stored energy in the magnetic field.
Common: µH (switching), mH (filters), H (coils/chokes).
Energy rises fast with current because it’s proportional to I².
Use when you want to force a specific output.
Show Work (step-by-step)
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Work is shown in base units (H, A, J) for clarity and consistency.

Inductor Energy Formulas

Core formula: stored energy in an inductor is E = ½ · L · I².

Solve for any variable:

  • Energy: E = ½ · L · I²
  • Current: I = √(2E / L)
  • Inductance: L = 2E / I²
Where E = joules (J), L = henries (H), I = amps (A).

FAQ

Why does energy scale with I²?

Because the magnetic field strength grows with current, and energy stored in the field grows with the square of field strength.

Does the inductor’s resistance matter here?

This tool models ideal stored energy. Real inductors also dissipate heat in copper resistance and core losses, especially at high current or high frequency.

What’s a “dangerous” energy level?

It depends on the circuit. Even small energy can create large voltage spikes if current is interrupted quickly. Use snubbers, flyback diodes, or proper clamps where needed.

Can I use this for motor windings?

Yes—if you know the winding inductance at the operating point. Many inductors/motors are non-linear (inductance changes with current/core saturation).

Tool Info

Last updated:

Updates may include UI improvements, unit support, and calculation edge-case handling.