18th century Quilted Velvet Petticoat. Gray.

Patterns: None. Rectangles and math. 
Fabric: Rayon velvet with cotton backing, pre-quilted. 

Measurements:
The waistband edges meet on either side on a 35" waist, so waist would depend on how much side overlap the wearer wants. More overlap, smaller than 35". No overlap, higher than 35". 

The hem is currently unfinished so I can take it up to the desired length of whoever buys it. 39" or shorter.

Pattern & Cutting

I started with 2.33 yards of the pre-quilted velvet. Cut in half, this gave me two panels 60" x 42". I happened to get a wide fabric, but a typical 54" wide fabric would work just fine. 

Since my design for this petticoat assumes the wearer will have a bum-roll or some kind of rump pad, I had to adjust the heights of the front and back accordingly. So, I cut away the center top of the front panel by 3" (this is because an average lift at the back with a rump/bumroll is about 3"). The 3" then scoops up to a 1" cutaway at the sides (red line indicates cutting)

It's best to do this cutting while the panel is folded in half length-wise, to make sure your cut is symmetrical. 

For the back panel, the cut away is really just the 1" at the sides, gradually curved up to the full length of the fabric and tapering off. The center back of the back panel will be the full length you cut. In my case, 42" long. 

Determining what dimensions to cut

Making a petticoat like this, quilted or otherwise, is just all simple math. First, the width that most modern apparel and home dec fabrics come in (54" to 60") already works perfectly for a petticoat, so width shouldn't be the issue (plus, you get to use the selvage on the side seams, eliminating the need to finish them).  To determine what length you'll cut, you need to figure out these numbers first:

1. Desired front length. I'm 5'7", but have short legs, so this for me is usually 36" to the ankle. 
2. The width of your hem. Wide hem? Narrow hem? I factored in 3" here, for a thick fabric. 
3. The "lift" you get at the back due to natural shape and/or bumrolls, rump pads, etc. Even if you plan to not wear them, you might have a natural lift of as much as 1.5" if you have a...ahem...particularly large backside (like I do). I factored in 3" at the back, assuming a bumroll. 
   
   So, once you have all those numbers, you just add all of them. 
   36" + 3" + 3" = 42" 
   You will cut two panels of 60"(fabric width) x 42". Then, proceed with the top cut alterations described above. 
   
   
   NOTE!...................................................................
   Those with smaller waists, say less than 30",
   may wish to cut away the top of the skirt so the
   panels are more angled rather than true rectangles.
   This is to reduce bulk of thick quilted fabrics at the waist.
   With smaller waists, the amount of fabric being pleated in
   will cause the pleats to start overlapping and become excessively
   thick with a pre-quilted fabric like this. 

Construction
There are few things simpler than an 18th century petticoat. Two rectangles, sewn together at the sides with about 9" left open at the top. Then front and back panels are then pleated to separate waistbands with ties on each end (four ties total for the petticoat) that will tie around the waist both back and front. 

(above) In the process of binding the front panel with the waistband. Because this quilted fabric is thick, I chose not to use more of the quilted velvet for the waistband. I instead used a gray cotton. Once bound, I went on to attach cotton tapes 22" long to either end. 

I also stitched down the side opening edges, doing a blind whip-stitch on the inside so no stitches showed through. One of the benefits of quilted fabric is that hemming and any kind of blind stitching is easy. 

FINISHED