The Magic of a Circle

I love geometrics. Garments with geometric shapes, prints with geometrics, geometrics in nature. Circles are among the most fascinating of creatures.

Circular skirts are the quintessential feminine garment. And you needn't have a pattern to create one. All you need is a bit of junior high math, an improvised compass, and some wide paper.

I learned about the magic of circular skirts (and ruffles...more on those later in the week) in one of my all-time favorite sewing books, Couture - The Art of Fine Sewing by Roberta Carr. I love this book so much I've considered buying a second in case anything happens to this one. If you can only buy one sewing book for the rest of your life, buy this one.

The magic formula for circles is this:
Circumference = 2 X pi X radius
or, C=2πr

π, if you remember your geometry (remember when you thought geometry would be useless in "real life?") = 3.14, so -

C=2(3.14)r or C=6.3r

Now lets say your waist is 30" around.

A circular skirt is really a ring, made up of an interior circle at the waist and exterior circle at the hem. The length of the skirt is the distance b/w the two. Both circles are drawn from the same center point. But the radius of the outer circle = the radius of the first + length of the skirt.

If the seamline of the waist opening is 30" then the inner circle circumference must be 30". You must also add at least one set of seam allowances to the circle's circumference so that you have an opening. Let's say we'll use SA's of 5/8" for a center back seam.

C = 30" + 5/8" + 5/8"
31.25" = 6.3r
r = 4.96"

Round that to a 5" radius and the world won't come to an end.

So you will draw the inner circle with a radius of 5"

The length of your skirt of course determines the distance of the outer circle from the inner. Perhaps you want a knee length skirt of 22" with a narrow hem allowance of 5/8". You will draw the outer circle with a radius of 5" + 22 5/8" = 27 3/8" from the center.

Note: When you have to draw a circle larger than the largest width of your compass you can improvise a compass by tying a long string to a pencil. Then measure the length of the string from the pencil and mark the radius you want, in our case 27 3/8", right on the string. Stab a pin through that mark and through the center of the pattern paper and swing the pencil around to draw the circle.

****Don't forget that the inner circle represents the waist seamline. You must also add a seam allowance above the inner circle for attachment to the waistband. (Yes, you can figure this into your calculations by subtracting the seam allowance from the radius of the inner circle, but since it's a small circle, I think it makes things simpler to just add it later.)

Once you have created your pattern and cut your fabric circle, you can cut a center back seam, preferably on an area of straight grain.

If you make a longer skirt, though, you may not be able to cut the entire skirt in one piece. You will have to cut two half circles or 4 quarter circles. You must take seam allowances into account when you are drafting. If, for example, you are going to cut the skirt in four pieces, you must add the width of 8 seam allowances to your original waist measurement. Like this:

W = 30"
SAs = 5/8" X 8
Circumference of inner circle = 30 + 5 = 35"
35" = 6.3r
r = 5.5"

Now you can draw your circles and divide them into four pattern pieces knowing that you've added in enough room for the 4 seams.

Perhaps you don't want your skirt quite as full as a whole circle. You can draft a half circle skirt. You will still need to circle your 30" waist, but with half as much volume in the skirt. You need to draft the inner circle twice as big as your waist so you can use only half of it. (For this skirt, I will add SAs after drafting b/c I simply can't get my mind around whether or not I should double those as well!)

C = 60
C=6.3r
60=6.3r
r=9.5"

Now you can draft a half circle with a radius of 9.5". Draft a second half circle for the hem plus hem allowance as above. Cut your pattern piece, and add seam allowance above the waist seamline and at center back.

Perhaps a full circle isn't full enough for you. You are tall and thin, like a human gazelle, like Heidi Klum. You can make a gathered circle skirt.

2X fullness would be about standard. But you want a fairly tale skirt in pink chiffon to wear under a silk corset bodice. So you're going to go for 3X fullness!

Simply triple the circumference of the inner circle. Obviously you will need to cut this skirt in several pieces, let's say 6 pieces.

W=30 X 3 = 90"
SAs for 6 gores = 12 X 5/8" = 7.5"
C inner circle = 97.5"
phew!
C=6.3r
97.5=6.3r
r=15.5"

Don't forget to add that waistline seam allowance now.

You're going to have to draft this one on the floor. Maybe in the front yard. But when it's done...WOW!

Next time...more circle skirt variations. Then...circular ruffles.

p.s. My brain hurts at this point. If you find a mistake in my calculations, by all means speak up!