The average delivery time for First Class mail in the United States is one to three business days. The United States Post Office ships First Class mail Monday through Saturday, and it must not exceed 13 ounces.
Personal correspondence, bills and marketing solicitations are commonly mailed First Class packages. The cost of a First Class stamp is 49 cents, and these can be purchased in singles as well as books. Priority Mail offers faster delivery times and is available in flat-rate boxes. This type of mail service delivers in one to two business days, accommodates larger packages and offers tracking numbers. Priority Mail also offers a delivery confirmation service.