Mature butternut squash comes in sizes ranging from 1 to 5 lbs. The average butternut squash will be around 2 to 3 lbs. After peeling and seeding, your squash will lose 2-3 oz of weight. For example, a 3 lb squash will yield about 2 lbs 13 oz of flesh. This is helpful to know for recipes that call for a certain amount of diced, peeled squash—if your recipe calls for 2 lbs of diced squash, you’ll want to look for a squash that is around 2 lbs, 3 oz in weight.