Enter your inductor's inductance (L) and current (I) to calculate the energy stored in the inductor. Choose your preferred units — from picohenries to henries and microamperes to amperes — and get the stored energy (E) output in joules using the formula E = ½LI².
Stored Energy (E)
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Stored Energy (mJ)
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Stored Energy (µJ)
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Stored Energy (nJ)
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The energy stored in an inductor is calculated using the formula E = ½LI², where E is the energy in joules, L is the inductance in henries, and I is the current in amperes. The energy is stored in the magnetic field created by the current flowing through the coil.
Inductors store energy in the form of a magnetic field. When current flows through a coil of wire, it generates a magnetic field around the inductor. As long as current continues to flow, the magnetic field is maintained and energy is stored within it. When the current stops, the magnetic field collapses and the stored energy is released back into the circuit.
Inductor energy is measured in joules (J). Depending on the size of the inductor and the current, the result may be more conveniently expressed in millijoules (mJ), microjoules (µJ), or nanojoules (nJ). This calculator displays results in all common unit scales simultaneously.
Energy stored in an inductor is directly proportional to its inductance. Doubling the inductance (L) while keeping the current constant will double the stored energy. Larger inductors — measured in henries rather than millihenries or microhenries — can store significantly more energy.
Current has a squared relationship with stored energy. This means doubling the current through an inductor increases the stored energy by a factor of four. This quadratic relationship makes current the most impactful variable in the E = ½LI² formula.
Inductors are used in switched-mode power supplies, DC-DC converters, filter circuits, and energy recovery systems. They act as surge protectors by resisting sudden changes in current, and they are key components in resonant circuits, transformers, and motor drives. Understanding the stored energy helps engineers design safe and efficient circuits.
Enter the inductance value of your inductor and select the appropriate unit (pH, nH, µH, mH, or H). Then enter the current flowing through the inductor and choose its unit (pA, nA, µA, mA, or A). The calculator instantly computes the stored energy in joules, millijoules, microjoules, and nanojoules using the formula E = ½LI².
Yes. The calculator supports inductance values down to picohenries (pH) and current values down to picoamperes (pA), making it suitable for high-frequency RF and microwave circuit design where component values are extremely small.