Contemplating Fitting Pants: My Alterations

originally published 2/3/12


It’s the once and forever quest, except this year I promised myself to try and understand why pants fit the way they do.  I need to start with some review.


Forever and ever it seems as though I had 2 complaints about pants.

  1. Some, but not all, did not come all the way up in the center back.
  2. Some, but not all, had this extra bubble in front.

I know I was not alone in these problems.  Well meaning individuals even told me “that’s the way some pants fit”.  I didn’t understand why some had to fit that way and some did not.  RTW got better, for me at least.  I seem to be part of a large demographic which suffered both those issues because as years went by I had less problems with RTW being too long in the front crotch and too short in the back crotch. RTW fixed itself. Pattern companies did not.  So for many years I folded out 1″ across the front crotch and added it to the back crotch. I never have problems with the front crotch beyond being sure that it is the correct length, so I will not make many references to the front pant pattern.  The back pant pattern is my greatest concern. (Schematic shows knee to waist)


So for many years I lengthened the back of my pattern piece using the standard recommended method of slashing across the pattern piece, starting on the center back about 2 inches above the crotch hook/extension and almost all the way to the other side.  I would then spread the slash apart, usually about 1″.  The resulting piece looked similar to this:

This one alteration made me happy with the fit and feel of my pants until a few years ago when I started taking pictures of my sewing creations and posting them on the Internet.  To my horror, I discovered that  every one of my pants had what I called a butt vortex.  I can’t find a picture on me but just imagine my pants being sucked into my an_l or_fice in kind of a swirling fashion.


Not attractive on a woman’s par of jeans.  Even the best of my pants, including all the RTW, at least dipped sharply into this area. This did not separate the booties and create a curvy rear end. Nope, I had a uni_but! with a vortex. This too has a standard recommended fix. Slash the pattern vertically about an inch from the tip of the crotch extension and spread the slash the needed amount:


This does fix any discomfort, but often causes another problem, that of diagonal wrinkles from knee to butt:


This last issues keeps me trying new patterns and new ideas for fitting pants. It simply goes away with certain patterns and most fabrics.  The question to me is why? Why does it occur at all? I want to say right now, that I am not knock-kneed.  That is a physical condition in which the knees turn inwards.  My knees are straight but I do accumulate a little fat around the inner knee that could be creating the same effect. Except, it doesn’t happen all the time.  Clearly the wrinkles are here in this medium weight, cotton/Lycra twill. Same pattern but a slightly lighter (still medium weight) and not twill but plain weave in chocolate brown does not have these wrinkles. Why?


Certainly, the fabric is a big factor and some fabric may simply not be good for use in the pant styles I want to wear. But I’m examining pattern pieces now. I’m looking to see why and which pattern pieces cause the issues. I’ll also say that the pant side seams are never eased. The inseams are eased from about the knee to the crotch. More or less easing could certainly have an effect. Back to the my standard alterations, I note that the pattern piece is distorted.  I never really realized, I should have but I didn’t,  that when adding edges I’m also adding to the interior volume. In this picture the original pant shape is placed on top and the colored area behind shows the volume added.


Let me try again with the altered pattern piece alone, but with the volumes added in a different color:

Do look between the two pics.  Note that the angle of the back crotch and the back extension has changed.  This new pattern piece has much more of a ski-slope shape for the center back.  The crotch extension originally possessed a mirrored J shape now it’s more of a downward slope. Also the side seam which was slightly curved inward has now juted to the outside effectively removing the dart that was at the side seam. However, the dart should now be included in the ski-slope center back. The width of the pant at the waist has not increased.


I  wonder but cannot at this time prove, is the volume being added settling beneath the rear as a result of gravity; stopping and being held above the close fitting knee. I do note that fuller pants and shorts rarely indicate these knee-to-thigh wrinkles. Even tighter pants will sometimes have a complete X, with the X centered over the knee. But again NOT ALL pants patterns will do this and sometimes these wrinkles only happen with certain fabrics. I mean I can take the same pattern, cut two pairs of pants from two different fabrics. One pair of pants will be perfect.  The other will have the wrinkles.  Obviously the fabric is having an effect.