how big is 1.5 cubic ft refers to a measurement of volume, often used in shipping to calculate the size of a package. One cubic foot is the volume of a cube with sides measuring 12 inches, and 1.5 cubic feet would be the volume of a space with a 12-inch by 12-inch by 18-inch dimension. This measurement is important when determining shipping costs, as carriers like USPS, FedEx, and UPS often use the size of a package in addition to its weight to calculate the shipping price. Knowing the cubic footage helps customers and businesses estimate the space required for storage or shipping and avoid unexpected costs.