The information in this post is from The Basics for Drafting & Fitting Pants and Skirts. Written by an industrial production pattern maker, tested in the college classroom with Continuing Professional Education Students, the book addresses all custom fit issues, including asymmetrical fit. Drafting instructions are included for inserted back pockets, inserted front pockets and front diagonal pockets with pocket stays, lining, and much more.

Combined with its companion book, The Basics for Sewing Pants and Skirts, the two books present the step-by-step, classroom-tested information you need to produce professional, beautifully fitted skirts and pants.

Below is an overview from The Basics for Drafting & Fitting Pants and Skirts. of how to measure, draft, and fit crotch depth:

Measuring the crotch depth

2-16: Measure the crotch depth by
having the person being fitted sit on a chair.
Write the measurement in
cell 18.

Complete the chart to determine how much depth
should be drafted into the pant pattern.
  1. Have the person being fitted sit on a chair that has no arms. Measure the crotch depth. 
  2. Write the measurement in cell 19 in Chart 2-17, Crotch Measurements.
  3. Add the desired amount of ease in cell 20, usually one inch.
  4. Complete Chart 2-17.
2-15: The crotch length 
starts at the body’s
center front at the waist,
continues down the
center front, around
the crotch, and up
the center back
to the center back
at the waist.

About crotch length

The pattern’s crotch length is the seam that runs down the center front from the waist, under the crotch, and up the center back to the waist. It combines vertical and horizontal lines. The desired crotch length is written in cell 18, in Chart 2-17, for future reference.
The pattern’s crotch length is longer than the body’s crotch length because the pattern’s crotch length includes ease.

Even if the crotch length is correct, the pants may not fit correctly through the crotch. That is because the crotch length is comprised of both vertical and horizontal measurements.

If the front and back vertical measurements are too long, the front and back horizontal measurements will be too short causing the crotch’s curves to pull in under the crotch.
If the front and back vertical measurements are too short, the crotch’s curves will be too high and may cause blousing above the hip line.
This diagram from The Basics for Drafting & Fitting Pants and Skirts
shows the pant patterns’ crotch length drafted over a skirt sloper
that was previously fitted on the model. 

    Drafting pants to fit involves three separate fitting areas

    Women have very different fit issues. Fitting pants can be a challenge. Drafting and fitting pants in the classroom with adult women has proven that fitting pants involves three separate fitting areas which are:
    1. The waist to hip area. Draft and correct this area to fit by drafting a skirt sloper (a basic pattern used in the industry to draft patterns for garment styles) to measurements, then cutting and fitting the skirt sloper in muslin.
    2. The crotch area. Draft this area from measurements over the skirt sloper, as shown in the diagram above, so as to incorporate the skirt muslin’s fit corrections into the pant pattern.
    3. The legs. Draft from measurements, then muslin fit the crotch and legs. The crotch area is affected by the fit through the legs. If the inseam at the knee is too tight, it will create pulls at the base of the back crotch area, a common problem seen in mass-produced pants. 

    Effective drafting, fitting, and sewing pants involves:

    1.  Careful measuring – charts are needed to record and determine measurements
    2.  Skillful fitting – transparent clothing in The Basics for Drafting & Fitting Pants and Skirtshows how the fabric lies over the body.
    3.  Precise sewing – step-by-step instructions in The Basics for Sewing Pants and Skirts show how top seamstresses in the industry’s designing departments produce high-end pants.

    Your comments are most welcome – Laurel

    If interested in reading more posts about fashion technology, please consider adding your name to this blog’s circles.
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    Look for the article about seam allowance modification that I wrote for Threads Magazine. It will be in their 199 issue that will be on the newsstands in late August (2018).

    Phone: 215 884 7065

    © Laurel Hoffmann, 2018. 

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