On average, laundry dryer balls made from wool last for about 1,000 loads or approximately 2-5 years. However, the lifespan of your wool dryer balls may be affected if you use fabric softener, live in a very dry or very humid environment, or frequently use them to dry “hard” items like shoes. You’ll know it’s time to replace your wool balls when they begin to look frayed and start to leave pieces of lint in your clothes.