Yardage and weight of a kilt?

[figheadair]

I was wondering, is there a good way to tell if a kilt is a 5 yard or 8 yard kilt, possibly by counting and measuring the widths of the pleats?

The simplest method is to run a tape along the length of the selvedge (bottom of the kilt). Quite often one finds that an 8 yard kilt has less material.

Also, is there a good way to tell the difference between a light (10-11 oz), medium (12-13 oz) and heavy (15-16 oz) weight kilts?

The best way is to get hold of a sample of each weight and feel the width/handle.