Ferrite Core Calculator

A ferrite core is the magnetic component at the heart of inductors and transformers used in power electronics — this Ferrite Core Calculator determines how many wire turns you need to hit a target inductance. Select your Core Type (E Core or Toroidal), enter your Required Inductance, Operating Frequency, core Dimensions, Air Gap Length, Relative Permeability, Wire Diameter, and Maximum Flux Density to get the required Number of Turns. Secondary outputs include Peak Current, Core Cross Section, Magnetic Path Length, Inductance Factor (AL), and Wire Length Required.

μH
kHz
mm

Core width dimension

mm

Core height dimension

mm

Core depth dimension

mm

Center post diameter

mm
mm
T

Results

Number of Turns

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Peak Current

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Core Cross Section

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Magnetic Path Length

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Inductance Factor (AL)

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Wire Length Required

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Frequently Asked Questions

What is the difference between E-core and toroidal ferrite cores?

E-cores have an open magnetic path making them easier to wind but less efficient due to magnetic leakage. Toroidal cores have a closed magnetic path providing higher efficiency and better magnetic shielding, but are more difficult to wind.

How does air gap length affect inductance?

An air gap in the magnetic path reduces the effective permeability and inductance. However, it also increases the peak current capability before saturation and makes the inductance more stable with temperature and current variations.

What is the typical relative permeability for ferrite cores?

Ferrite materials typically have relative permeabilities ranging from 500 to 10,000. Higher permeability materials provide more inductance per turn but saturate at lower current levels.

Why is maximum flux density important in inductor design?

The maximum flux density determines when the core will saturate. Beyond this point, inductance drops dramatically and the inductor becomes ineffective. Typical ferrite cores saturate around 0.3-0.4 Tesla.

How do I choose the right wire diameter for my inductor?

Wire diameter should be chosen based on current carrying capacity and available winding space. Thicker wire carries more current but takes up more space, potentially limiting the number of turns.

What factors affect the peak current rating of a ferrite core inductor?

Peak current is limited by core saturation and depends on the number of turns, core cross-sectional area, air gap length, and maximum flux density of the ferrite material.

How does operating frequency affect ferrite core selection?

Different ferrite materials are optimized for different frequency ranges. Higher frequencies may require materials with lower permeability but better high-frequency characteristics to minimize core losses.

What is the inductance factor (AL value) and how is it used?

The AL value represents the inductance per turn squared (nH/N²) and is a measure of how much inductance each turn contributes. It depends on core geometry, material permeability, and air gap length.