USPS business days are Monday through Saturday. Sundays and federal holidays are not counted as business days, which means no regular mail collection or delivery happens on those days. When USPS quotes a delivery window like “2 to 5 business days,” only Monday through Saturday count toward that estimate.
How USPS Counts Business Days
Understanding how USPS counts business days matters most when you’re trying to figure out when a package will arrive. The count starts the day after your item is accepted and processed, and it skips Sundays and holidays entirely.
Here’s a practical example straight from USPS: if you send something with a 3-day service standard on a Friday, the expected delivery date is Monday. Friday counts as the acceptance day, Saturday is day one, Sunday is skipped, and Monday is day two… but USPS actually lists Monday as the delivery date in this scenario because the count begins the next business day after mailing. If you send that same 3-day shipment on a Saturday, Sunday gets skipped entirely and the expected delivery date pushes to Wednesday.
This is where people often get tripped up. A “3-day” service standard doesn’t mean 3 calendar days. It means 3 days where USPS is actively processing and delivering mail. A shipment mailed on a Thursday before a Monday holiday could take noticeably longer on the calendar than one mailed on a Tuesday during a normal week.
When Drop-off Time Matters
The time of day you hand off your mail also affects which business day starts the clock. Every USPS collection box and Post Office lobby has a posted last collection time. If you drop something off after that cutoff, it won’t be picked up and processed until the next postal business day.
So if the last collection at your local Post Office is 5:00 p.m. and you drop a package at 5:30 p.m. on a Tuesday, USPS treats it as though you mailed it on Wednesday. That effectively adds a full day to your delivery window. If you need a shipment to go out same-day, check the posted collection time at your drop-off location and get there before it.
Saturday: A Business Day, but Different
Saturday is officially a USPS business day. Mail carriers deliver regular mail, and Post Office retail counters are open (though usually with shorter hours than weekdays). Saturday counts toward transit time calculations just like any weekday.
That said, Saturday can function a little differently in practice. Some smaller Post Office locations may have limited Saturday hours or close entirely. If you’re planning a Saturday drop-off, confirm your local branch’s hours before making the trip.
Sunday and Holiday Delivery Exceptions
While Sunday isn’t a business day for standard mail, USPS does deliver certain items on Sundays. Priority Mail Express, the fastest USPS service, offers Sunday and holiday delivery in many major markets for an additional fee. Amazon packages delivered through USPS also frequently arrive on Sundays in many areas.
These exceptions don’t change how business days are calculated for other services. If you’re shipping via Ground Advantage, Priority Mail, or First-Class Mail, Sundays and holidays are still skipped when counting your delivery window.
Federal Holidays USPS Observes
USPS does not deliver mail or count the following days toward business-day transit times:
- New Year’s Day
- Martin Luther King Jr. Day
- Presidents’ Day
- Memorial Day
- Juneteenth
- Independence Day
- Labor Day
- Columbus Day
- Veterans Day
- Thanksgiving Day
- Christmas Day
When a holiday falls on a Sunday, USPS typically observes it on Monday. When it falls on a Saturday, the observed day is usually Friday. Either way, that observed day is removed from the business-day count, which can extend delivery times around holiday weekends by more than you’d expect.
Quick Way to Estimate Delivery Dates
If you want to figure out when something will arrive, USPS offers a service standards calculator on its website. Enter the origin ZIP code, destination ZIP code, and mailing date, and it will tell you the expected delivery date with holidays and Sundays already factored in.
For a rough manual estimate, count forward from the day after your mail is accepted. Include Monday through Saturday, skip Sundays and any federal holidays in the window, and you’ll land close to the expected arrival date. Just remember that the acceptance date itself depends on whether you made the last collection time at your drop-off point.