An elastic waistband that is too tight digs into your stomach and makes you uncomfortable. You can loosen an elastic waistband by adding to the length of the elastic or by weakening the elastic so that it does not pull as tightly. You can delay buying new clothes for your growing children by loosening the waistband in skirts, trousers and shorts. Add length by lowering the hem or adding a band of contrasting fabric to the hem.
Remove 3 inches of the casing seam with a seam ripper. Pull out the elastic and cut it.
Cut a new piece of elastic 3 inches long and pin the ends of it to the ends of the elastic waistband. The elastic should be the same width and type as the current waistband elastic. Cut a longer piece of elastic if you wish to add more than 3 inches to the waistband.
Try on the garment and pin the elastic tighter or looser as desired. Because all elastic stretches differently, trying on the trousers is the best way to get the fit you desire.
Sew the ends of the elastic together, as pinned, so that they overlap 1/2 inch. Zigzag over the ends on each side with a 1/8-inch wide stitch. Cut off any excess elastic. Be sure the elastic waistband is not twisted. Resew the casing seam.
Snip the top strand of elastic cording in the waistband every 3 inches along the length of the band using sharp pointed scissors.
Snip the fourth row of elastic cording in the same way, placing the cuts 1 inch further along the waistband so that the cuts do not line up across the width of the band.
Continue cutting every fourth row in the same way, varying the placement of the cuts as before.
Try on the garment, If it is not loose enough, cut the elastic cords that lie midway between the rows you cut earlier. Cut the cord in the same way.