CORE AL · INDUCTANCE · WHOLE TURNS
Ferrite Core Inductance & Turns Calculator
Use the AL value of your actual core assembly to calculate inductance or whole turns. Compare the inductance range from AL tolerance, or derive an effective AL from a measured coil.
Calculate ferrite-core inductance or winding turns
Live resultsMETHOD & ASSUMPTIONS
Calculate inductance from the core AL value
Calculation method
The AL value describes inductance per turn squared for a specified core assembly and test condition. Use the value for the actual material, geometry, air gap and assembly.
The target-inductance mode compares whole-turn choices. A nominal target calculation and a turn count sized for the AL lower bound answer different questions; both are shown separately.
Scope of this estimate
These are initial small-signal estimates using the AL value you enter. A generic permeability value is not a substitute for the core assembly’s AL.
The AL tolerance is propagated through the calculation. It is not a prediction of the effects of DC bias, temperature, frequency, assembly variation or saturation.
This tool does not determine saturation current, core loss, power rating or transformer insulation requirements. Confirm the chosen winding and core by measurement under the intended conditions.
WORKED EXAMPLE · NOT A PRODUCT SPECIFICATION
Example: AL = 100 nH/turn² and 20 turns
A core assembly with AL = 100 nH/turn² gives a nominal inductance of 40 µH with 20 turns. If AL tolerance is ±10%, the calculated range is 36–44 µH. Using 22 turns to reach at least 40 µH at the AL lower bound gives 43.56–53.24 µH across that same AL interval, so it does not fit a 40 µH ±10% target window. These are small-signal estimates for the supplied AL interval.
BEFORE YOU SPECIFY
Common design questions
Where should the AL value come from?
Use the manufacturer’s data for the exact core assembly, including its specified gap and test conditions, or derive an effective AL from a measured inductance and known turn count.
Why are there different whole-turn suggestions?
Rounding up the ideal turn count reaches the nominal target. Designing against the AL lower bound may require more turns, and that can increase the upper end of the inductance range. Check both ends against your target tolerance.
Does this predict inductance under DC load?
No. AL may vary with DC bias, temperature and frequency. The tool only propagates the AL and tolerance you supply; it does not estimate saturation or core loss.
Does the minimum-AL option guarantee a finished coil's inductance?
No. It checks the stated AL interval with the chosen whole-turn count. The result still depends on the actual core assembly and the test conditions. Check both the lower and upper inductance limits, then measure the finished winding under the intended conditions.
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