How to Make an Infinity Dress

Taking Measurements and Doing Some Mat

Before you can order your fabric, you'll need to figure out how much you need. This is largely determined by the length of the skirt.

Measuring

First, take the following measurements:

• Waist = w inches

• Skirt length = L inches

• Height = h inches

• Breast/chest width = b inches (this should be the amount of fabric needed to cover a single breast or pectoral, with some overlap at the center)

• Breast/chest height = t inches (the amount of fabric needed to line the strap from bottom of a single breast or pectoral to wherever makes you feel comfortable)

• s = seam allowance (I will be using 1/2 inch)

Measuring on your own? Clip hem clips or binder clips to your sewing measuring tape around where you think you want the skirt length. Then, hang the tape from your waist and use a mirror to decide which marker is the correct length. Adjust and repeat as needed.

Now we can do some math!

Skirt Math

Let w = waist measurement = skirt opening circumference

What we need to find is the radius of the opening so we can draw it out on fabric. Because the fabric we'll use is stretchy AND cutting a circle skirt causes most of the lines to be on the bias, we'll subtract one inch from the measure before finding the radius (included in the equation below). We'll also let π = 3.14 for the sake of rounding.

To find the radius, use the following equation:

r = (w -1) / 6.28

Remember your order of operations! Do the subtraction before the division. For my waist measurement of 33 inches, this gives a radius r = 5.09 inches. Round down to the nearest quarter inch - for me that's 5 inches.

Next, we must account for seam allowance. Take r - s to get the final radius of the skirt opening. For my measurements, that's 4.5 inches. This is the radius I will use when actually drawing out my pattern.

The last piece of the skirt is the length as measured from the opening. This is simply L. For me, L = 35 inches. As long as your fabric will not fray, there's no need to account for seam allowance as you won't need to hem it. If you want to hem it anyway, use L + s instead.

Strap Math

The other measure we need is how large to cut the straps. This is pretty straightforward and the easiest way to get the right ballpark measure is to use height, h.

To get our strap length, use 1.5 x h. For me, that's 1.5 x 67 inches = 100.5 inches. Round down to the nearest inch (100 inches).

This was ultimately a bit long and I trimmed the straps by 10 inches after finishing the rest of the dress. Again, we will not need to hem the straps as long as we use fabric that will not fray.

To get the width of each strap, simply use b inches (width to cover one breast/pectoral). We will need some seam allowance in this direction because we're going to line the first part of the strap. So the final width will be b + 2s. For me, this measurement was 14 + 1 = 15 inches.

The final measurements for your straps are then (1.5h) by (b + 2s), remember you will need two straps!

To line the straps, the lining will be the same width as the strap (b + 2s) with a height of (t + s) as only one end of the lining will be stitched. If you plan to use power mesh as a middle layer of the lining, this is the dimension needed for that as well. For me, this gives 15 inches by 10.5 inches for the lining.

Notes on Materials

I also recommend looking for a good drape. The fabric should fall elegantly over your body and around your shoulders. This is particularly important for the straps which will need to be able to twist and bunch up easily.

Generally speaking, if the fabric meets the requirements above, it's going to travel well and shouldn't wrinkle easily. This is key for the straps which will be scrunched up and manipulated heavily, allowing you to change the style of the dress at any time. No wrinkles here!

Finally, check the cut edges to make sure it won't fray. Again, if it's meeting the requirements above, this should not be an issue. In a perfect world, the edge won't curl either but that's much harder to find.

I used Telio Brazil Stretch ITY Jersey in Wine from Fabric.com (now owned and operated by Amazon.com).

Power Mesh

I wanted a little bit of support in the straps and decided to line the first bit with some power mesh to provide it. Power mesh is a mesh fabric that stretches well in one direction but not at all in the other. This means one direction can be used to provide support while the other direction continues to be stretchy and comfortable. It's a great choice for lining athletic wear and knit lingerie. This characteristic also makes it a great fit for breast/chest support in dresses when you won't want to wear a bra. Note, however, that it will do nothing for nipple control.

In total, you will only need enough to cut out the lining, so ordering 1/2 - 1 yard should be enough. I bought mine on Fabric.com (now owned and operated by Amazon.com). The color is currently out of stock but it's available in many colors by searching "power mesh."

Making an Infinity Dress

Now that you have your cutting diagram and all your supplies, let's make the dress! Follow the steps below.

Step 3 - Do It Again

Repeat steps 1 and 2 on the opposite end of the fabric. You should now have two half circle skirt pieces and two straps.

Step 4 - The Remaining Pieces

Cut out the lining and pocket pieces using the remaining fabric. Reference your measurements from above. My lining was 15 inches x 10.5 inches.

Remember to also cut the lining out of the power mesh, if you will use it, paying close attention to the direction the fabric stretches. The stretch should go across the chest with the non-stretch direction going up and down the body.

Pause and Prep the Machine

Now that we're ready go sew - go prep and check your machine. *Make sure there is a ballpoint needle in the machine,* the stitch is set to zig-zag or stretch stitch, and the tension is behaving itself.

Originally published September 9, 2022.