Despite the abundance of clothing stores selling pajamas, it can be hard to find the right fit for pajama pants. If the waist fits properly, often the legs will be too tight, and if the legs are comfortable, often the waist will be too loose. Many people will opt for a size that is too large rather than buy a size that is too small. The easiest way to fix a loose-fitting pair of pajama pants is to insert an elastic waistband into the waist lining.
Turn your pajamas inside-out. Lay your pajama pants on the table and press out any folds or wrinkles. Fold the top of the pants near the waist over about 1 inch and then fold it once more another inch. This fabric will encase the elastic waistband.
Place the long elastic waistband around your waste and pull for a tight but comfortable fit. Add one inch to this length of the waistband and cut the excess length off with a pair of scissors.
Sew the two ends of the elastic waistband together using a sewing machine so that one inch overlaps and is sewn together.
Place the elastic waistband inside the fold you made in the pajama pants so that it is encased in the fabric. Sew along the bottom of the fold and the waistband using a sewing machine. Once that line has been sewn all the way around, Sew along the top end of the fabric using the sewing machine. This will anchor both sides of the elastic to the inside fabric of the pants. Turn the pants right side-out.