The length of time that 20lbs of Wooden pellets will last in a pellet stove is dependent upon quite a few things, including the effectiveness with the stove, the burn off rate, and also the temperature setting. On common, a pellet stove will burn off amongst 1-3 pounds of pellets https://woodbrezany.com/en/how-long-does-40lb-bag-wood-pellets-last/