priority mail how much refers to the cost of sending a package via USPS Priority Mail, which offers faster delivery than First-Class Mail. The price for Priority Mail starts at $8.70 for small flat-rate packages and increases based on the weight and size of the package. USPS also offers larger flat-rate boxes for heavier items, with prices up to $21.50. For standard Priority Mail, delivery time typically ranges from 1 to 3 business days, depending on the destination.