usps 1st class rate is the cost of sending packages via USPS’s First-Class Mail service. This is one of the most economical ways to send small and lightweight packages within the United States. First-Class Mail is typically used for letters, postcards, and lightweight parcels, and it offers a cost-effective shipping solution for both businesses and individuals. The rate for First-Class Mail varies depending on the size, weight, and destination of the package. It is an ideal option for sending documents, small items, or lightweight goods while ensuring a fast delivery time.