Pants Fitting - the missing link??

I've just had a pants-fitting A-Ha! moment, and I want to capture it before it escapes my brain....

This week I bought "Fitting and Pattern Alteration" by Elizabeth Liechty, Judith Rasband and Della Pottberg-Steineckert.  I haven't had a good look at it yet, but last night I glanced through Chapter 6,  where it shows you how to alter the crotch curve on pants using your own body space, which you find by holding a flex-curve to yourself.  I already had a template of my body space (strange, but true), which I made up after reading the Threads articles on this topic.  The diagrams in Threads showed that I had  tilted pelvis, but did not really show how to correct for this.

Anyway, I thought I would follow the Liechty et al method and compare my body space to patterns that already fit me well (for the purposes of understanding the process, rather than to start with a pattern that doesn't fit and try to correct it).  I compared it to 2 patterns, my Alice & Olivia wide-legged pants and my Marfy close-fitting jeans.

Figure 1 is a mud-drawing of the body space sitting inside the Alica & Oliva pants.  It fits really nicely inside the crotch curve.  The only problem I have with these pants is strain on the CB seam below the waistband, and I guess I correct this by adjusting the slope of the CB Crotch seam. It also seems I have a slightly "receded pubic area", which is a new phrase to me!

Figure 2 is a mud-drawing of my body space inside the Marfy jeans and it shows that there is not enough room.  How can this be, when the jeans fit beautifully?  I came up with a few different possibilities

1.  The jeans are made up in a stretch denim.  True, but I got out the muslin, which was made in a woven, and it fits too.

2.  Jeans sit between the bum cheeks and not over the top of them.  Again, true, but doesn't seem to account for all the missing space.

3.  This body space theory has not been fully explained, because the crotch curve changes from being parallel to the body at the CF, perpendicular to the body through the lower crotch curve and back to parallel to the body.  So I put the muslin on, found the point where the fabric moves from parallel to perpendicular and compared that to the the shape of the bottom of the crotch curve.  Still not enough length.

And 4....stick with me...this is my A-Ha! moment.  The diagrams in this fitting book, and Threads, always show the pant front and back with the grain line vertical on the page.  But this is not how the fabric sits on the body, because the curved leg seam will put strain on the fabric in this region.  Not so much in wide-legged pants where the inner leg seam is fairly straight (and hence the Alice & Olivia scenario) and much more so in tight fitting pants.  So I slid the back pants piece around so that the leg seams on front and back sat next to each other.  Finally, the crotch curve matched my body space, except for the section where the jeans sit between the bum cheeks.  This makes sense (well, to me anyway) because jeans follow the bum curve to a much lower point than wide legged trousers, which will hang from further up the curve.

So, did anybody follow this?  What do you think? 


  1. Very interesting.

    I have never seen anything like the diagram you presented above before, but it does not surprise me because I know what lengths people will go to for the perfect fitting pair of pants, and all those alterations have to come from somewhere!

  2. I'm sure your correction will work but I had to laugh. My DD was looking over my shoulder and asked "Why are you looking at blogs about birth control?".

  3. Well done! Mueller also agrees with you so you are in excellent company. ;) Mueller has always advocated that you must match the pants along the inseam in order to check your crotch curve. Just as you concluded. I have never agreed with the Threads way of doing it. It doesn't make sense as you discovered. :)

    Oh btw, this method of comparison only relates to the bottom curved part of the crotch curve. There is more theory that relates to the CF and CB seam (straight section). Too detailed to go into here though.

  4. It's like you were reading my mind!

  5. Brilliant! Gotta love diagrams.

  6. I totally want that book. Much luck fitting those pants.

  7. Thank you so much for posting this. I am a visual learner and your diagrams really made sense to me!