# Re: Formulas

```Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Mddeming-at-aol-dot-com>

In a message dated 2/15/01 1:48:41 PM Eastern Standard Time, tesla-at-pupman-dot-com
writes:

>
> Original poster: "Jason Johnson by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <hvjjohnson13-at-hotmail-dot-com>
>
> Does anyone have a formula for calculating the AWG size of a wire from the
> diameter (preferably in inches), and/or a formula for the number of turns
> per
> inch based upon the AWG? I need these formulas for an excel spreadsheet so
> the
> simpler they are the easier it is for me to put them in. They need to have
> fairly good accuracy (+/- 1% or less). Also I haven't really looked around
> for
> them yet, but if anyone has any formulas for inverse conical (saucer shaped)
> primaries I could use those too.
>
> Jason Johnson
>
>

Hi Jason,
Try this for a close-wound coil:  h=0.3176*N*exp(-0.1104*G)
G= AWG Number    N=Number of turns in coil        h=height of winding in
inches
It should be pretty accurate for sizes 6 to 40, but some people close-wind a
little tighter than others.
Matt D.

```