what is the cost for flat rate shipping is a question many online sellers and buyers have when looking to ship packages at a fixed price regardless of the weight, as long as the item fits within a designated box. For example, USPS offers flat-rate shipping for Priority Mail, where the price is determined by the size of the box, not the weight (up to a certain limit). The cost of flat-rate shipping depends on the service used and the destination of the package. USPS provides a variety of flat-rate boxes, and each has a different cost depending on whether you are sending it domestically or internationally. For domestic shipments within the United States, flat-rate boxes typically start at around $8.50 for a small box, and the prices increase for larger boxes. When shipping internationally, the costs can range from $25 to $70, depending on the destination country and the size of the box. Flat-rate shipping is often a convenient option for sellers and shoppers who want to avoid the complexities of weight-based shipping calculations and want predictable costs for their shipments.