Lets say you want to make a skirt, six panels, wider at the top than the bottom. Let's say you want to use up as much of your fabric as you can. If you can get two strips of fabric that have a height of the length of the skirt, here is how to cut the panels.
For my example, I am using 2 yards (72") of fabric. After
cutting off a bit for the waistband, I have two rectangles that are
If you were going to make square panels, it would look like this:
Where the width of each square was equal to 1/3 of the total length (24" x 3 = 72" total).
But, you don't want to make square panels. You want trapezoids. You want it to look like this:
So the question is, what are the measurements of the trapezoids?
1. Take the total length of your fabric and divide by 3. This is measurement A.
2. Divide A by 10 and round up. This is measurement B.
3. The small side of the trapezoid (will be the top of the skirt) is A-2B. This is measurement C.
4. The long side of the trapezoid (will be the bottom of the skirt) is A+B. This is measurement D.
5. The distance between the edge of the fabric and the small side of the trapezoid is D-C divided by 2. This is measurement E.
So, in my example:
A= 72" / 3 = 24"
B= 24/10 = 2.4 (round to 3)
C= 24" - 6 = 18"
D= 24" + 3"= 27"
E= 27-18/2 = 4.5"
Two yards is plenty of fabric for a skirt. I have a 44" waist, and this will still be 2.3x bigger than my waist at the top. This skirt will be nice and poofy. If you are working with a less ample fabric size, you will need to make sure that Cx6 is bigger than your waist, even accounting for seam allowances.
I almost never actually work out exact patterns and cutout plans before I buy fabric, which means that most of my patterns are worked like this, starting with the dimensions of what I've bought, rather than buying to match the dimensions of the pattern.