This paper addresses the determination of the size of storage bins in a warehouse system and the number of storage bins of each size. The sizes of products that are stored in the warehouse are diverse and different according to the products. The warehouse needs several size types of storage bins to store products that are different in size. The maximum inventory amount of each product size type is normally distributed with known mean and variance. The size and the number of storage bins that minimize the total cubic size of storage bins in the warehouse have to be determined. The problem is analyzed and a mathematical model is formulated. And a dynamic programming algorithm is developed. A numerical example is shown to explain the algorithm.