2-2.5 cm. The outer diameter of bamboo tube zongzi molds varies, and most of them are 3-3.5 cm in diameter for commercial use. The made zongzi is relatively large, and the diameter of 2-2.5 cm is relatively small, which is suitable for family use. Mold is a tool for making zongzi, usually made of bamboo. Using this mold can make the shape of zongzi more beautiful, and can better retain the fragrance and taste of zongzi.