priority mail usps rates are based on the weight, size, and destination of the package. USPS Priority Mail provides fast and affordable shipping with delivery typically within 1 to 3 business days. For domestic shipments, Priority Mail rates start at around $8.70 for a small package weighing up to 1 lb. Rates increase based on the weight of the package and the destination. USPS also offers flat-rate boxes for Priority Mail, where the shipping cost is the same regardless of the weight, as long as the package fits within the specified size of the box. The smallest Priority Mail flat-rate box costs approximately $9.65, while the largest box costs around $21.90. USPS Priority Mail includes free tracking, delivery confirmation, and $100 in insurance for lost or damaged items. International shipping with USPS Priority Mail starts at approximately $26.90, depending on the destination country. For those who need expedited shipping, Priority Mail Express offers overnight delivery at a higher rate, starting at $26.35 for domestic shipments. USPS Priority Mail is popular for both personal and business shipping needs due to its balance of affordability and speed.