Proper fabric treatment can prevent your laundry from coming out of the wash a size or two smaller. Some fabrics are particularly prone to shrinkage, especially if you wash them in hot water and then tumble them in a machine dryer. Wool, linen and rayon should be dry cleaned or hand washed, or at least washed in cold water, and allowed to air dry. Lay heavy fabrics like wool flat to dry, as they may stretch if hung. Cotton garments sold today are typically preshrunk, notes "Real Simple" magazine, so you can get away with washing them in warm or cold water and drying in a clothes dryer without noticeable shrinkage.
How to Stop Laundry From Shrinking
Remedying Shrunken Clothing
Clothes shrink because the fibers in the fabric coil up. You may be able to restore shrunken clothing to its original size. Knits made of wool, cashmere or cotton are most responsive to restoration. Relax them by soaking the shrunken garment in water and a capful of baby shampoo or hair conditioner, recommends "Real Simple." Remove the garment from the soaking liquid and wring out the excess water gently. Place it on a flat surface and coax the clothing back to its original size by stretching it carefully. A steamer can help if the garment is still resistant to stretching; use a similarly sized item as a pattern if you aren't sure of the original dimensions. Once stretched, weigh down the edges with a heavy object until the garment dries completely.