Every day except Sunday is a USPS business day. Local office hours vary from 8 a.m. to 6 p.m. Monday through Friday, but some offices close earlier. Check your local post office hours before visiting. USPS delivers on Saturday, although it has short business hours and is closed on Sundays, and on federal holidays.

In 2026, the United States Postal Service (USPS) generally considers Saturday a standard delivery day for most of its mail services, distinguishing it from private carriers like UPS or FedEx which often charge surcharges for weekend arrivals. While Saturday is a "working day" for mail carriers—meaning Priority Mail, Priority Mail Express, and even standard Ground Advantage packages are routinely delivered—it is not always classified as a "business day" in the traditional corporate or legal sense. For example, the USPS retail post office locations often have significantly limited hours on Saturdays, frequently closing by noon or 4:00 PM, and they do not process "business day" transit calculations for certain money orders or international shipping guarantees in the same way they do from Monday through Friday. Consequently, while your package may arrive on a Saturday, many shipping estimates and legal notification periods will skip Saturday when counting the total number of "business days" required for a service to be completed.