Components & Devices calculator
Inductor Calculator
This inductor calculator covers the basic checks most engineers, technicians, and students need when working with coils and inductive components. Use it to convert inductance units, calculate inductive reactance, combine uncoupled inductors in series or parallel, estimate stored energy, and get a single-layer air-core coil estimate from turns and geometry.
Updated July 10, 2026
XL = 2πfL, so a 10 mH inductor at 60 Hz is about 3.77 ohms
Stored energy = 1/2 LI² | 1 mH at 2 A stores 0.002 J
Choose reactance, stored energy, combination, or air-core coil mode below
Example Calculations
More examples. Open to review 2 additional calculation examples.
How to Use
How to use the inductor calculator
Select the mode that matches your task, enter the required values, and review the result in the unit shown on the page. The calculator is intended for practical component checks and early circuit work, not for detailed magnetic core design or vendor-specific part selection.
Supported calculation modes
| Mode | Main Formula | Typical Use |
|---|---|---|
| Inductance conversion | Unit conversion between H, mH, μH, and nH | Component comparison, documentation, and schematic cleanup |
| Inductive reactance | XL = 2πfL | AC impedance checks, filter review, and frequency response estimates |
| Stored energy | E = 1/2 LI2 | Current ramp checks, switching stages, and basic magnetic energy review |
| Series or parallel inductors | Lseries = L1 + L2 + ... | Equivalent inductance for uncoupled parts in prototype circuits |
| Air-core coil estimate | Wheeler single-layer coil estimate | Quick first-pass geometry checks for round air-core coils |
What the reactance result means
Inductive reactance is the opposition an ideal inductor presents to alternating current. It increases in direct proportion to both frequency and inductance, which is why the same part may look nearly transparent at low frequency but much larger in impedance as frequency rises.
If you are checking a complete AC network instead of a single ideal inductor, follow up with the Impedance Calculator. For capacitor pairing, resonance checks, or RC timing work, the Capacitor Calculator and RC Circuit Calculator cover the adjacent circuit math.
When the coil estimate is appropriate
The air-core coil mode is a quick estimate for single-layer round coils. It does not model ferrite cores, iron powder cores, toroids, shielding cans, winding resistance changes from wire gauge selection, or vendor-specific tolerances. Use it for layout planning and prototype checks, then compare the final design with measured data or supplier information.
Common Applications
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Frequently Asked Questions
What is the difference between inductance and inductive reactance?
Inductance is the property of the component itself and is measured in henries. Inductive reactance is the impedance that inductance creates at a specific AC frequency and is measured in ohms. The reactance depends on both frequency and inductance through XL = 2πfL.
How do series and parallel inductors combine?
For uncoupled inductors in series, the total inductance is the sum of the individual inductances. For uncoupled inductors in parallel, you add the reciprocals and then invert the result, just as you would for resistors in parallel. If the parts are magnetically coupled, the simple parallel or series formula may not match the real circuit.
What does the stored energy formula tell me?
The stored energy formula E = 1/2 LI² shows how much energy is held in the magnetic field at the selected current. It is useful for first-pass checks in switching converters, pulse circuits, and current ramps, but it does not replace current-rating, saturation, or temperature verification.
When should I use the air-core coil estimate?
Use the coil estimate when you want a quick single-layer air-core result from turns and coil geometry. It is useful for concept work and prototype planning. It is not a substitute for detailed ferrite, iron powder, toroidal, or vendor-specific magnetic design.
Why can the measured value differ from the calculator result?
Real inductors include tolerance, winding resistance, parasitic capacitance, proximity effects, fixture capacitance, and frequency-dependent behavior. Coil geometry and nearby metal can also shift the measured value. The calculator is best used as a clean first-pass check before measurement.
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