For coils of other types, see the Downloads Page for calculators in spreadsheet form.

If that is not displayed, then try using a different browser.

Pitch p is centre to centre spacing between windings (measured parallel to the coil axis).

The units for all dimensions, except conductor diameter, are according to the pop up menu at the top of the calculator.

The conductor diameter is either mm or AWG according to the units pop op adjacent to the conductor size input field.

Select the either Pitch or Coil Length from the pop up menu, and then enter the corresponding p or value into the input field.

This field is optional, but makes it convenient to specify close wound coils.

To do this, leave the Winding PitchCoil Length field blank or set to zero, and enter the overall wire diameter into the d i field.

You still need to enter the conductor diameter.) When you click the Calculate button, the pitch and coil length will be adjusted to appropriate values for a close wound coil.

In addition, if you enter a conductor size d w or overall wire diameter d i that is too large for the specified pitch or coil length, the pitch and coil length will be increased automatically to the minimum close wound dimension.

If you are using standard enamelled magnet wire, you can check the Auto Calculate box, and the overall diameter for this type of wire will be calculated automatically, based on the conductor size.

Calculation of enamel thickness is based on typical magnet wire used by hobbyists, and may vary slightly from the actual value due to different insulation temperature ratings which affects insulation thickness.

For single turn loops, Maxwells elliptic integral formula is used.

The single turn formula does not require round wire corrections.

The following coil cross-sectional diagram shows the proper measurements.

The number of turns may be counted conveniently on the side away from the leads.

Since it may be inconvenient to measure from wire centre to centre, the dimensions shown on following diagram may be used to measure and calculate the effective dimensions.

Then, the effective coil diameter, D, is the average of the two, given by.

For example, for a coil with 5.3 turns, measure the outside to outside length 2, and subtract od to get the centre to centre length of 5 full turns.

Then multiply the result by 5.35 to get the length of 5.3 turns.

Air Wound Coil Resistance Calculator