Almost anyone who has done laundry and then put on their jeans knows that something happens in the washing process to make the jeans smaller. The simplest explanation is that the jeans shrink from the heat of the wash water and the dryer. Even prewashed jeans shrink a little bit in the wash. The only way to avoid shrinking jeans is to wash them in cold water and hang them to dry. It is much easier to plan ahead by buying Levis that are a size larger and one to two inches longer than needed and shrink them.
Purchase a pair of Levis. If you buy them with the intent of shrinking them at home, make sure the ones you purchase are a little bit loose (one size too large) and a little bit long (one inch too long).
Place the jeans in the washing machine on a warm or hot water setting, and allow them to go through the machine's cycle.
When the washing machine cycle is complete, put the Levis in a dryer and set it on a high heat cycle. Allow the dryer to run until the jeans are completely dry.
If you buy new Levis Shrink to Fit 501 jeans instead of regular Levis, add one inch to the waist size if your waist measurement is less than 36 inches, add two inches to the waist size if your waist measurement is more than 38 inches, and add three inches to the length you need. Levis Shrink to Fit 501 jeans shrink up to 10 percent.