Straight Side Seams and Pant Balance: Insights from the Topo Pattern (Part 3)

In Part 1, I introduced the Topo Pant pattern from Leila Makes and discussed how to find the drapelines and balance lines (kneeline and crotchline). What makes this pattern unique is that the front piece has a curved side seam while the back has a straight side seam. In Part 2, I adjusted the front pattern to have a straight side seam, aligned the side seam lengths, and made sure the front and back drapelines were parallel. While these changes improved the fit when seated, the drapelines still weren’t vertical.

After some internet sleuthing into pant balance, I discovered that the bottoms of the crotch curves should be on or within 1/2 inch of the same horizontal level. In the original pattern, the back crotch is 2 inches lower than the front, which is too much.

I turned to IG to ask whether I should raise the back crotch or lower the front. Here’s a summary of the suggestions I received:

• The back crotch might be lower than the front because of negative ease in the back inseam between the crotch and knee.
• Back crotch and inseam often need to be shorter than the front for improved shaping around the butt.
• The crotch points on pants (especially men’s) don’t always need to be level.
• Pants don’t need to be perfectly balanced since everyone’s body is unique.

From this, it became clear there was some confusion about leveling crotch curves and inseam lengths. Just because the crotch curves are level doesn’t mean the inseams will match *foreshadowing*. Inseam length and crotch curve placement are two separate, although related, concepts.

The amount of inseam curvature will impact the length. On the left, you can have inseams where the bottom of the crotch curve is on the same level, but the inseams are different lengths. The straighter the inseam, the shorter it will be. Alternatively, you can have inseams where the bottom of the crotch curve is not on the same level, but the inseams are all the same length (right side). So, to review, the inseam length and crotch curve leveling are two separate items to check when assessing pant balance:

1. The bottom of the crotch curves should be on the same level, or the back crotch can be up to 1/2 inch lower than the front. The front should never be lower than the back.
2. The front and back inseams should be the same length, or the back can be up to 1/2 inch shorter. The front should never be shorter than the back.