Inductor Energy Storage Calculator

An inductor stores energy in the magnetic field created by current flowing through its winding. The stored energy is E = 1/2 L I squared, where E is measured in joules, L is inductance in henries, and I is current in amperes. The one-half factor reflects how the magnetic field builds as current rises from zero to its final value. This simple relationship is fundamental to power electronics, electromagnetism, and circuit design. Current has a squared effect on energy. Doubling current increases stored energy by a factor of four, while doubling inductance only doubles energy. That distinction matters when checking peak current in switching converters, motor windings, relays, and pulsed electromagnets. Even a physically small inductor can hold meaningful energy when it carries high current. Conversely, a large inductance operated at a tiny current may store very little energy. In a buck or boost converter, the inductor repeatedly accepts energy from a source and releases it to a load. Designers calculate peak stored energy to select an appropriate core size and saturation-current rating. If the core saturates, effective inductance falls and current can rise rapidly. The calculated energy is also useful when estimating snubber requirements, switch stress, and the consequences of suddenly interrupting current. Because an inductor resists abrupt current change, opening a circuit can create a large voltage unless the energy has a controlled discharge path. This calculator assumes an ideal inductor whose inductance remains constant at the entered current. Real components lose some energy through winding resistance, core hysteresis, and eddy currents. Their inductance may vary with current, temperature, and frequency. Use the peak current rather than average current when checking maximum energy in a switched circuit, and consult the manufacturer's inductance-versus-current curve for a saturated core. The result gives the magnetic energy at one instant; it is not power. Power describes the rate at which energy moves and requires a time interval or switching frequency. Within these limits, the formula provides a clear and reliable first estimate for laboratory, educational, and engineering calculations.