price of if it fits it ships boxes refers to the cost of using USPS’s “If It Fits, It Ships” flat-rate boxes. These boxes allow customers to ship items of any weight, as long as they fit inside the designated box, for a fixed price. USPS offers several sizes of flat-rate boxes, each with a predetermined shipping cost based on size rather than weight. This service is popular for businesses and individuals who need to ship items quickly and economically, as it eliminates the need for weight-based pricing and provides predictable shipping costs.