Maybe your wool pants are too long in the legs, or maybe they're too loose around the waist. Whatever the case, you would like to shrink them so they fit better. Wool is a natural fiber that's prone to shrinking. According to the American Wool Association, unless a wool garment has a special tag inside that says it can be machine washed, it will surely shrink.
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Wash your wool pants in hot water in the washing machine to shrink them. According to Time.com, the elasticum (inner layer) and the core of wool shrink and pull the cortex (outer layer) in when they are washed in water. The shrinkage can range from 10 to 30 percent, depending on the type of fabric.
Toss your wool pants in the dryer after you wash them. Use the regular heat setting to dry them. The heat, in conjunction with being tossed around, will shrink them.
Hang the wool pants up and use a handheld steamer to steam them. Pay particular attention to areas you want the fabric to shrink. The steam (heat and water) will shrink the wool pants. When you've finished, lay the pants flat and allow them to air dry.
Another option is to hang your wool pants up in the shower away from the shower head so they don't get drenched. Then take a hot shower and let the steam shrink the wool. When you're done, take the pants down and lay them flat to air dry.
If the wool pants contain more than 50 percent wool, they are still likely to shrink.
Shrinking wool can make the fabric feel rough. The wool pants may not be comfortable to wear after you shrink them.
Shrink wool pants and they'll be out of shape, so they won't fit the same. They'll likely lose their sheen too.