Swayback Adjuster
Fix the horizontal fold or gap at center back waist. The same tapered wedge adjustment applies to bodices, skirts, and pants backs.
Identify your swayback amount
Choose how you want to determine the adjustment amount — directly from a fitting muslin, or from body measurements.
How deep is the horizontal fold when you pin it flat at CB?
What is swayback?
Swayback (also called lordosis in posture terms) is a natural variation in the lower back curve. People with swayback have an inward curve at the lower back that pulls the fabric up at center back — creating a horizontal fold or gap just above the waist, while the side seams hang normally.
The standard pattern is drafted for a relatively flat lower back. On a swayback body, there is too much fabric at center back — the pattern is longer at CB than the body is. The fix removes a wedge that is deepest at CB and tapers to nothing at the side seam, matching the amount of extra length to the curve of the back.
Swayback affects every garment with a back waist seam — bodice backs, skirt waistbands, and pants waistbands. Once you know your swayback amount, apply it consistently.
Swayback vs. other CB waist issues
Swayback: Horizontal fold just below the waistband at CB, deepest at center back, while the side seams hang straight. The fold is parallel to the waist.
Back rise too long (pants): Similar appearance on pants but extends lower — the fabric bags through the seat, not just at the waistband. Use the Rise Calculator for this.
Waistband too big: Gaping around the entire waistband, not concentrated at CB. Fix by taking in the waistband evenly.