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Inductor Calculator
Estimate an air-core coil’s inductance from its winding dimensions, or estimate how many turns reach a target. Free to use in your browser.
How do I estimate coil inductance?
For a single-layer circular air-core coil, the calculator applies Wheeler’s approximate formula using mean winding diameter, winding length and whole turns. For example, 40 turns on a 20 mm diameter, 50 mm long winding with 0.8 mm wire gives about 10.68 µH.
Frequently asked questions
How do I estimate coil inductance?
For a single-layer circular air-core coil, the calculator applies Wheeler’s approximate formula using mean winding diameter, winding length and whole turns. For example, 40 turns on a 20 mm diameter, 50 mm long winding with 0.8 mm wire gives about 10.68 µH.
Are my coil dimensions uploaded?
No. The estimate runs in this browser. Coil dimensions and target values are not uploaded or saved by this tool.
Can this calculate an iron-core or multi-layer inductor?
No. It uses a Wheeler approximation for one circular air-core layer. A core or multiple layers change the magnetic field and require a different model.
Why does doubling turns increase inductance by about four times?
In this model inductance is proportional to the square of turn count, as long as the coil geometry and single-layer assumptions remain valid.
Does wire diameter change the inductance result?
It is only used to check whether the requested turns can fit along the entered winding length in one layer. The formula does not model wire thickness, insulation or spacing in detail.