Start with your hip measurment.

Then subtract the apron width.

divide the remainder by the pleat reveal measurment.

This will give you the no. of pleats.

Build the kilt using your hip measurment. Make all the pleats even and straight.
The taper is in the fell area only and should come out to equal your waist.
(Waist measurment minus apron width divided by no. of pleats will equal the pleat width at the waist.)

Wash your fabric before cutting in warm water with about a half cup of Downey. Repeat about six times. Then into the dryer on cotton setting.
Then and only then cut to length.

Hope that helps. If not, call me.