1845 illustration from "Costumes of the Clans." The garment is described as "made of sufficient length to reach from the neck to the ankles & being nicely plaited all round, fastened at the waist with a belt & secured on the breast by a large brooch.
This style of kilt has to be pleated by hand each time you put it on. Essentially, it is just a length of double-width tartan. The length can vary from to 9 yards, but 6 or 7 yards is the most popular choice. The Great Kilt shown here is 7 yards.