Facebook Email Pinterest Twitter X Instagram Tiktok Icon YouTube Icon Headphones Icon Favorite Navigation Search Icon Forum Search Icon Main Search Icon Close Icon Video Play Icon Indicator Arrow Icon Close Icon Hamburger/Search Icon Plus Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon

Adjusting Women’s Pants With This On-the-Body Fitting Method for the Back-Crotch Seam

You’ll be amazed at how precisely and easily it locates and fixes areas of poor fit.

Fit the crotch curve directly

Here’s an on-the-body fitting method that is odd to execute but is uniquely helpful in showing you exactly what fitting adjustment is needed at the back-crotch seam. You’ll be amazed at how precisely and easily it locates and fixes areas of poor fit.

1. Expose the back-crotch seam and allowances. With your full muslin, place one leg inside the other, with the seam allowances on the outside. Put on the pants and anchor them with elastic at the waist. Check that the crotch seam is centered on the body.

2. Assess the pants back. If you have problems with the HBLs dipping or the grainlines bowing, you’re likely to see fabric crumpled under the buttocks and in several places on the back inner thigh.

3. Clip the crotch seam. Clip into the seam allowances as far as, or even a good deal beyond, the seamline. As you work, you’ll feel tightness along the seamline, indicating where you should clip. Clip until the crumpling disappears and tension is released.

Clipping the crotch seam releases tension and eliminates wrinkles. By clipping, you reshape the crotch seam exactly as needed for the body. This is a straightforward method for creating the scooped and/or lowered crotch curve that many figures need for an optimal pants fit.

4. Redraw the crotch curve. When the fabric lies smooth and flat, draw the back-crotch curve, following the body’s form and indentations.

5. Adjust the pattern. Transfer this new seamline to the pattern and make a new muslin. Try it on, and make any additional alterations; you may need to add width at the side seams to compensate for what was lost in scooping and/or lowering the crotch seam.

This is an excerpt from the article “Improved Pants Fitting” by Sarah Veblen (p.54) in Threads #195.


Threads Insider

Get instant access to hundreds of videos, tutorials, projects, and more.

Start Your Free Trial

Already an Insider? Log in


  1. Remnants | | #1


  2. User avater
    ustabahippie | | #2

    Wish I could do this on myself🤣

  3. user-7060053 | | #3

    Can you clarify in step four, how do you get the spacing correct where you've slashed the fabric before you redraw the crotch line?

    1. carolfresia | | #6

      The slashes will leave a sort of "fringe" along the back crotch curve. Lay the pants back flat and arrange the "fringe" as neatly as you can. Then draw the new seamline to connect the base of all the cuts. You can use a fashion curve as a guide to neaten that line a bit when you transfer it to the pattern tissue.
      Carol Fresia, Threads Senior Technical Editors

  4. user-214638 | | #4

    I tried this for two pairs of linen pants I wanted to make for holidays. Usually my partner helps me with pattern fitting, usually not very successfully (or happily). I showed him the video that accompanies this. The results were terrific. I had to make further minor adjustments, and the fit isn’t perfect, but I have the best fitting pants I’ve had since putting on weight. Sarah Veblen is a goddess.

  5. User avater
    user-7682503 | | #5

    Thank you for this helpful article. What do HBLs stand for?

    1. carolfresia | | #7

      HBLs are horizontal balance lines. These are explained in the original article from which this explanation comes. To fit a pants muslin, draw lines perpendicular to the grainline across each section at about hip level; if desired, make two or three parallel lines. When you try on the pants, if the HBLs dip at center back, that tells you that you'll need a fit adjustment.
      Carol Fresia, Threads Senior Technical Editor

  6. User avater
    user-7682503 | | #8

    Thank you Carol !

Log in or create an account to post a comment.

More From Threads

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |

Threads Insider Exclusives

View All
View All