Self Drafted Long Underwear with Gusseted Crotch


I used the leftover fabric from my Winter Weight Crew to make up a pair of bottoms for this upcoming winter. I was able to draft a successful pattern that includes ankle cuffs, waistband, and a crotch gusset for increased mobility. 

The pattern was drafted off my own measurements, with 6 inches of ease at the waistband for a stretchy, loose fit. I originally wanted a loose fit through the legs, but drafted the pattern a bit tight. For instruction, I used Helen Joseph Armstrong’s book, Pattern Drafting for Fashion Design.


The pattern is pretty straightforward: two fronts, two backs, two cuffs, one gusset, and one waist band (not pictured). The original draft above has excess ease in the fronts, which was removed later.

Most of the commercially produced sports garments have gusseted crotches to increase hip mobility, which I have failed to reproduce, until know. Designing and sewing the gusset is much easier than I once thought, and only involves the inseam.

To start, I serged the pant fronts together, and the back pants together at the front and back seams. After that, I pinned the center of the gusset to the back half of the pants, and then sewed it in place with a straight stitch.


With the middle in place, distribute the gusset material to either side of the inseam, keeping the gusset centered.

With the first half of the gusset sewn in, I laid the front half of the pants, right sides together with the back half, and gusset. Starting in the center of the inseam (the crotch), I matched the front center to the center of the gusset and pinned. Working down either side, I pinned the rest of the inseam, and sewed it all together.


Here you can see how the inseam seam allowances branch away from each other at the gusset, and then re-united on the other side. It’s important to keep each of the seam allowances separate from each other at the edges of the gusset, so they can be serged appropriately.

To finish the gusset seams, I serged one side of the gusset first, beginning and ending on a SINGLE seam allowance of the inseam. This is the red line below. This line of serging only extends a little beyond the ends of the gusset.


The blue line represents the final serge of the entire inseam. Starting at one ankle run both seam allowances through the serger up to the gusset. At the gusset, make sure you pick up your first serged inseam and incorporate it into serging for a clean, strong finish.


Here is the finished gusset from the inside, and the outside. I zig-zagged the seam allowance to keep it flat.


The rest of the pants went together quickly. There was too much fabric in the upper front, and so I trimmed about and inch out to help the fit. I just ran the chalk line through the serger.


The ankle cuffs are a standard design, in which a single piece of fabric is sewn into a circle, then folded  in half, before being sewn onto the leg. The cuffs are cut about 2 inches narrower than the end of the pant to snug in the ankles.

The waistband is created with the same design as the ankles, and is roughly 6 inches narrower than the top of the pants. I placed elastic inside the waist band also.


I’ve had elastic twist up inside waist bands before, and to prevent that I straight stitched through the elastic to hold it in place. To ensure that elastic still has room to move, I stretched out all the ease while I sewed, using a 3.0mm stitch length. When the fabric is relaxed, the longer stitches shrink up.


There’s plenty of room for improvement in the fit of the pattern, but the knit fabric makes up for it. If I make another pair, I’ll increase the width of the legs a couple of inches, add an inch to the length of the seat, and add an inch or two of leg length.


3 thoughts on “Self Drafted Long Underwear with Gusseted Crotch

  1. These look amazing! The fit is perfect! Gussets are also used in some vintage garment sewing as a way to give ease of movement at the underarm. I have an old dress of my Mom’s with such a gusset, same size as yours, and it is put in exactly as yours, but as I mentioned, they are to allow for movement under the arm.

    Excellent drafting and sewing these! Thanks for sharing! 🙂


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