Pants Waist Alterations by Machine

Pants waist alterations are another common task in costuming. If costume pants are too large in the waist, you can easily alter them by machine.

Menswear makers usually design men’s pants with a center back seam in the waistband. The reason for this construction is to allow pants to be more easily altered. Because the side seams of men’s pants include pockets and other details, you should attempt to do all pants waist alterations through the back seam if possible.

1. To determine the amount of waist alteration you need to make, try the pants on the actor. Then pull back a section at the back center waist seam until the waist fits comfortably. 
2. Place a safety pin or mark where the adjusted seam should go.
3. Measure 2 inches past this on each side (away from the center seam) and mark

4. At the back center waistband seam, rip out the seam that holds the waistband facing down on the inside of the pants between the marks
5. With ripped waistband section turned up, make a new seam at the New Seam Mark, through waistband and facing

6. Continue alteration through back pants seam, tapering before the curve into the crotch
7. Trim extra fabric in seams if needed (if seam is too bulky – usually not the case) 
8. Steam-press seam open
9. Fold waistband back into place, and machine-tack in place
10. Steam-press one more time through all layers