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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).

What Is an Inductor in Electronics?

An inductor is a passive electrical component that stores energy in amagnetic field when electric current flows through it. Inductors are one of the fundamental building blocks of electronic circuits and are widely used inpower supplies, filters, transformers, RF circuits, and energy storage systems.

Inductors are typically made from a coil of conductive wire wrapped around a core material such as air, ferrite, or iron. When current flows through the coil, a magnetic field forms around the conductor. This magnetic field stores energy that can later be released back into the circuit.

One important property of inductors is that they oppose changes in current. When current attempts to increase or decrease rapidly, the inductor generates a voltage that resists that change. This behavior makes inductors extremely useful for stabilizing electrical signals and smoothing power supplies.

Engineers frequently use tools like an inductor calculator to determine inductance values, voltage behavior, and stored magnetic energy when designing electronic circuits.

Understanding how inductors work is essential for anyone studyingelectronics, electrical engineering, or power system design.

Inductor Voltage Formula Explained

The voltage across an inductor depends on how quickly the current flowing through the inductor changes over time. This relationship is described by theinductor voltage equation.

V = L × (di/dt)

This formula shows that the voltage generated by an inductor is proportional to therate of change of current. If the current changes rapidly, the inductor produces a higher voltage to oppose that change.

  • V = Voltage across the inductor (Volts)
  • L = Inductance (Henries)
  • di/dt = Rate of change of current (Amperes per second)

This behavior is often referred to as electromagnetic induction. It explains why inductors resist sudden current changes and help smooth electrical signals in many circuits.

In practical circuit design, this equation is used when analyzingRL circuits, switching regulators, power electronics, and signal filters.

Energy Stored in an Inductor

When current flows through an inductor, energy is stored in the magnetic field surrounding the coil. This stored energy can be released back into the circuit when the current decreases.

E = ½ × L × I²

This equation calculates the total magnetic energy stored in an inductor.

  • E = Stored energy (Joules)
  • L = Inductance (Henries)
  • I = Current flowing through the inductor (Amperes)

Because the energy depends on the square of the current, increasing current significantly increases the amount of stored magnetic energy.

This property is especially important in applications such asswitching power supplies, DC-DC converters, and energy storage circuits. In these systems, inductors temporarily store energy and release it during different phases of the switching cycle.

Current (A)Inductance (H)Stored Energy (J)
10.50.25
20.51
30.52.25

Common Types of Inductors

Different electronic applications require different types of inductors. Engineers choose specific inductor designs based on factors such asfrequency, current capacity, core material, and size.

Inductor TypeDescription
Air Core InductorUses air as the core material. Ideal for high-frequency RF applications.
Iron Core InductorProvides higher inductance values and is commonly used in power systems.
Ferrite Core InductorUsed in switching power supplies and high-frequency circuits.
Toroidal InductorCompact design with low electromagnetic interference.

Choosing the correct type of inductor ensures optimal circuit performance and helps minimize losses caused by resistance and magnetic saturation.

Applications of Inductors in Modern Electronics

Inductors play a critical role in many electronic devices and electrical systems. Their ability to store magnetic energy and resist rapid current changes makes them essential components in modern circuit design.

Some of the most common applications of inductors include:

  • Switch-mode power supplies (SMPS)
  • DC-DC voltage converters
  • Electronic filters and signal processing circuits
  • RF communication systems
  • Energy storage circuits
  • Electric motor control systems

In power electronics, inductors smooth current flow and reduce voltage ripple. In communication systems, they are used in tuning circuits that select specific frequencies from radio signals.

Because inductors are fundamental components in electrical engineering, engineers frequently rely on tools such as an inductor calculatorto estimate inductance values, analyze circuit behavior, and design efficient electronic systems.

Understanding inductance and inductor behavior helps engineers design more efficient power systems, communication devices, and electronic products.

Frequently Asked Questions

What is an inductor?+

An inductor is an electronic component that stores energy in a magnetic field when electric current flows through it.

What does an inductor calculator do?+

An inductor calculator helps determine voltage, energy storage, inductance, and current behavior in electrical circuits.

What is inductance?+

Inductance is the property of a conductor that opposes changes in current by generating an induced voltage.

What is the formula for inductor voltage?+

The voltage across an inductor is calculated using V = L × di/dt, where L is inductance and di/dt is the rate of change of current.

How is energy stored in an inductor?+

Energy is stored in the magnetic field created by current flowing through the inductor coil.

How do you calculate energy stored in an inductor?+

Energy stored in an inductor is calculated using E = ½ × L × I².

What unit is inductance measured in?+

Inductance is measured in Henries (H).

Why do inductors oppose changes in current?+

Changing current produces a changing magnetic field, which induces a voltage that opposes the change according to Lenz's law.

What is Lenz's law?+

Lenz's law states that induced voltage opposes the change in current that created it.

What is magnetic flux?+

Magnetic flux describes the total magnetic field passing through a given surface area.

What materials are used in inductors?+

Inductors are commonly made from copper wire coils wrapped around air cores, iron cores, or ferrite cores.

What is an air-core inductor?+

An air-core inductor uses air as the magnetic core and is commonly used in high-frequency circuits.

What is a ferrite-core inductor?+

Ferrite-core inductors use ferrite material to increase inductance and improve efficiency.

Where are inductors used in electronics?+

Inductors are used in filters, power supplies, transformers, radio circuits, and switching regulators.

What is inductive reactance?+

Inductive reactance is the opposition an inductor provides to alternating current and depends on frequency and inductance.

What is the formula for inductive reactance?+

Inductive reactance is calculated using XL = 2πfL.

What happens to inductors in DC circuits?+

In steady DC conditions, inductors behave like short circuits after the current stabilizes.

What happens to inductors in AC circuits?+

In AC circuits, inductors continuously oppose current changes and create inductive reactance.

What is the difference between inductors and capacitors?+

Inductors store energy in magnetic fields, while capacitors store energy in electric fields.

What is an RL circuit?+

An RL circuit contains a resistor and an inductor and is commonly used to analyze transient current behavior.

How are inductors used in power electronics?+

Inductors regulate current, filter signals, and store energy in switching power supplies.

What industries use inductors?+

Inductors are used in telecommunications, power systems, automotive electronics, and consumer electronics.

Can students use inductor calculators for learning?+

Yes. Students studying physics and electrical engineering commonly use inductance calculators.

Is this calculator suitable for real inductors?+

This calculator assumes ideal behavior, while real inductors may include resistance, saturation, and core losses.

Who should use an inductor calculator?+

Electrical engineers, electronics technicians, students, and hobbyists often use inductor calculators.