You may need to go over the area with the seam ripper a few times to cut all the stitches open. Adding a gusset to an existing pair of pants may be necessary if they are too tight in the crotch and you want to make more room, or if the fit is a bit off. [1] X Research source If you are making a pair of pants from a pattern, then the pattern will indicate how to cut the pants with allowances for a gusset. In this case you will not need to worry about opening up a seam. Just follow your pattern’s instructions for cutting the pants pieces.
If you do not have a pattern, then you will need to measure to determine how much space you will need. Have the person who will be wearing the pants put them on and then measure the gaps in the fabric between their legs and going from the front of the crotch to the back of the crotch. [2] X Research source Record your measurements and add a 1” seam (2. 5 cm) allowance to each measurement. For example, if you decided that the gusset needed will be 3” (7. 6 cm) by 1” (2. 5 cm), then add 1” (2. 5 cm) to each measurement for a total of 4” (10 cm) by 2” (5 cm). Gussets are small square or diamond-shaped pieces, so you will likely only need a piece that is about 4” to 5” (10 cm to 12. 7 cm) long and 2” to 3” (5 cm to 7. 6 cm) wide. Square gussets are best cut on the straight grain of the fabric, which will mean all your seams will be on the straight grain, ad the gusset itself will have a little bias stretch front-to-back and side-to-side.
Remember that you are using your measurements to determine the distance between each point of the diamond. The longest measurement will be from one point of the diamond to its opposite point and the shortest measurement will be from another point of the diamond to its opposite point.
Remember that the gusset’s longest part should go from the front to the back of the crotch.
Remove the pins as you sew.
If the gusset seems too large, then you can take it in a bit. If it seems too small, then you can take it out a bit. If the fit looks and feels good, then you can sew your permanent stitch over the baste stitch.
For example, if you want the gusset to be a little looser, then you can pin the gusset into place with a ½” (1. 3 cm) seam allowance rather than with a 1” (2. 5 cm) seam allowance. If you want the gusset to be a little tighter, then you can pin the gusset with a 1 ½” (3. 8 cm) seam allowance. After you have re-pinned your gusset, sew it into place again with a baste stitch, and have the person try on the pants again. If you are happy with the fit, then move on to sewing the gusset into place. If the fit is still off, then you can adjust the gusset again. Keep in mind that if the gusset piece is very ill fitting, then you may need to start over and measure and cut out a whole new piece.
To backstitch, press down on the lever on the side of your machine and hold it down for a few seconds. This will reverse the direction of your fabric. Then, release the lever and sew forward to the end again. Be careful not to sew over the edge of the gusset because this may lead to puckering. Sew right up to the edge of the gusset piece and do not go past it. [8] X Research source
Keep your pants turned inside out while you are tacking down the seam allowances. Remember that this is optional, but it may increase the comfort of your pants.
After you finish cutting the excess thread, your gusset is ready to go! Finish sewing your pants if needed, or try them on if you only needed to add the gusset.
