The way clothes fit obviously depends on their style and construction, but the principles described here apply in most cases.
DARTS AND SEAMS
You can take in all garments by increasing the amount of fabric taken at the seams or other shaping areas such as darts, tucks, pleats or gathers. To let out garments reduce the amount taken at these places. Unfortunately on many modern manufactured garments, this may present a problem because the amount allowed for seams is so small.
As well as the affected seams or darts, you may have to unpick and remove a waistband or seam joining a skirt to a bodice to give access to the area. You may also have to remove zip fasteners. These can all be re-inserted after the alteration.
The alteration must not affect the balance of the garment. The total amount to be let in or out should be halved between the left and right hand sides so that the centre front or back lines are not moved. If you alter a dart at the left front, you must alter one on the right front to correspond.
If you alter darts or seams on a skirt, you will probably also have to adjust the bodice of a dress or waistband.
Gussets If you cannot let out seams enough, particularly at underarms or at the waist, you could insert a triangular gusset of matching fabric.
Decide how much you wish to let out. Cut a triangle to fit, plus 1 cm (3/8 inch) seam allowance all round.
Unpick the seam to be altered to the required depth and open it out by the re quired amount. Place the triangle under the opening and tack and stitch neatly in place.
If altering the underarm seam of a bodice, repeat the process on the sleeve seam and then resew the sleeve to the bodice.
If altering the seams on a skirt or trousers, increase the waistband as described below and resew the waistband in place.
Alterations to seams and darts will also affect the waistband. Turn the waistband inside out at the under-lap end, removing any hooks and eyes, to see its construction. To reduce the length you can usually sew the required distance from the end. To increase length you may have to join on a piece at the end. If you are lucky, the new piece may form the underlap of the opening.