Inductor Calculator — Voltage, Energy & Inductance CalculatorV = L·di/dt · E = ½LI² · Henries · Amps · Volts · Joules · Time Constant
Use this free Inductor Calculator to instantly compute key inductor electrical parameters using the two fundamental inductor equations in electrical engineering and circuit theory. First, calculate the induced voltage across an inductor using Faraday's Law of electromagnetic induction: V = L × di/dt — where V is the induced voltage in Volts (V), L is the inductance in Henries (H, mH, or μH), and di/dt is the rate of change of current in A/s. Second, calculate the energy stored in an inductor's magnetic field: E = ½ × L × I² — where I is the peak current through the inductor in Amperes (A)and E is the stored magnetic energy in Joules (J). Enter any known values across Henries (H) · millihenries (mH) · microhenries (μH) to solve all remaining inductor circuit parameters.
These inductor formulas are foundational across all areas of electrical and electronics engineering: DC-DC converter & switching power supply (SMPS) inductor sizing · LC, RL & RLC filter circuit design & resonant frequency calculation · boost, buck & flyback converter energy storage calculation · transformer & coupled inductor design for power electronics · inductive energy storage in motor drives & solenoid actuators · RF choke, EMI filter & signal integrity inductor selection. This online inductor calculator is trusted by electrical engineering students, power electronics engineers, PCB designers, RF engineers, electronics hobbyists, Arduino and embedded systems developers, and physics educators for accurate inductance, voltage, energy, and RL time constant (τ = L/R) calculations in both DC and AC circuit analysis.
⚠ Engineering Disclaimer: This inductor calculator assumes ideal inductor behavior with zero DC resistance (DCR) and linear, non-saturating magnetic core operation. Real-world inductors deviate from ideal behavior due to DC winding resistance (DCR losses), core saturation at high currents, core hysteresis and eddy current losses, self-resonant frequency (SRF) limitations, temperature coefficient of inductance, and parasitic capacitance. For safety-critical power electronics design, high-frequency RF circuits, or precision filter applications, always verify inductor specifications using a calibrated LCR meter and consult the manufacturer's datasheet and a licensed electrical or power electronics engineer following applicable IEC, IEEE, and JEDEC component standards.
Calculate Voltage (V = L * di/dt) and Energy (E = 0.5 * L * I²).
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Inductor Calculator — Inductance, Energy, Impedance, and Time Constants
Inductors store energy in a magnetic field and resist changes in current. Inductance L is measured in Henrys. The energy stored in an inductor is E = ½LI² — a 10mH inductor carrying 5A stores 0.125 joules. Unlike capacitors that oppose voltage changes, inductors oppose current changes. This property makes inductors essential in power supply switching regulators (where they smooth output current), radio frequency filters (where they block high-frequency signals), and motor drivers (where back-EMF must be managed).
Inductive reactance XL = 2πfL defines how much an inductor impedes AC current at a given frequency. A 1mH inductor has 0.628Ω reactance at 100 Hz, 6.28Ω at 1 kHz, and 62.8Ω at 10 kHz. This frequency-dependent impedance is what makes inductors work as low-pass filters — they pass low frequencies with little attenuation but increasingly block high frequencies. The calculator computes reactance across a frequency range so filter behavior can be visualized before building.
The RL time constant τ = L/R governs how quickly current builds in an inductive circuit. A 100mH inductor with 10Ω series resistance has τ = 10ms. After one time constant, current reaches 63.2% of its final value; after five time constants, 99.3%. This timing affects motor startup characteristics, relay pickup time, and solenoid actuation speed. Parallel and series inductor combinations follow the same rules as resistors — series inductances add directly; parallel inductances combine inversely.