. Sandbags Bags are made from various materials, but the most common is woven polypropylene. They usually measure about 14 inches wide and 24 to 26 inches long. Other sizes of bags... also are available, but bags are easier to handle if their weight with filling in them is limited to 35 to 40 pounds. Sand is the easiest material for filling and shaping sandbags.... Silt and clay in bags will form a good dike, but working with those materials is more difficult. Fill sandbags slightly more than one-half full. Contact your county emergency...