Key takeaways
- USPS delivers First-Class Mail in 1–5 days, and Saturdays count
- For a date instead of a range, enter both ZIP codes and your mailing date in the USPS Service Commitments tool
- A letter mailed on Saturday or the day before a holiday is expected later, because USPS leaves that Sunday or holiday out of the count
- USPS sets the service standard for each pair of 5-digit ZIP codes, so distance alone won't tell you the day
- For a money-back delivery guarantee, check Priority Mail Express terms; ordinary Priority Mail is an estimate. Certified Mail adds mailing and delivery records, not faster delivery.
USPS delivers First-Class Mail in 1–5 days. Where your letter lands in that window depends on the ZIP code it leaves from, the ZIP code it is going to and the day you mail it. For a date instead of a range, enter both ZIP codes in the free USPS Service Commitments tool (opens in new tab). It returns the expected delivery day for your letter.
The official USPS delivery window: 1–5 days#
USPS lists First-Class Mail as “Mail delivered in 1–5 days” on its First-Class Mail page (opens in new tab). The number for a specific letter is its service standard: the days USPS expects delivery to take once it has accepted the letter. No First-Class Mail service standard is longer than 5 days.
First-Class Mail has an expected delivery date, not a guaranteed arrival date. For a delivery date with a money-back guarantee, USPS sells Priority Mail Express, covered under faster options below.
USPS delivery time calculator: estimate the delivery date for your ZIP codes#
USPS has two free lookups that estimate delivery from your ZIP code. Start with the first one when you have a specific letter to send.
- Service Commitments (opens in new tab) asks for the ZIP code you are mailing from, the ZIP code you are mailing to, the date and the time of day. It returns the expected delivery day for each mail class.
- Transit Time Map (opens in new tab) asks for a mail class and the ZIP code you are mailing from. Choose “First-Class Mail Letters and Flats”, then drag and zoom the map to the area you are mailing to.
How to read the result#
In the results, scroll to the table headed First-Class Mail letters. Skip the shorter First-Class Mail table above it, which can show a different date. On the First Class Mail Letters row, the date under Expected Delivery Day is when USPS expects to deliver a letter mailed on the date and time you entered. For nearby ZIP codes that row can appear twice with two dates; plan on the later one. The tool has already applied the Sunday and holiday rule described below.
The Transit Time Map shows the service standard on its own, without your mailing date. Count the days from the day you mail and apply the Sunday and holiday rule yourself.
Use the day USPS gets the letter as your mailing date. If you print and stamp it yourself, check the last collection time before choosing that date. If you send the letter online with Postmarkr, the letter is printed the next business day and mailed from the print facility, not from your address, so a lookup from your own ZIP code does not describe it. Allow time for printing followed by USPS's estimated 1–5 days. Even allowing all 5 days does not guarantee arrival by a deadline. Postmarkr sends First-Class Mail only; it does not sell the faster or signature services described further down.
How USPS counts the days: Saturdays, Sundays and holidays#
USPS's First-Class Mail page says 1–5 days; some of its help pages say 1–5 business days. In USPS's own examples, a Saturday or a Sunday in transit counts as a day. The exception is a Sunday or holiday that falls right after the day you mail. Under “Exceptions apply” on the Transit Time Map (opens in new tab), USPS says: “If you send mail on a Saturday or the day before a holiday, the Sunday or holiday is not included in the expected delivery time.”
USPS gives two examples for a letter with a 3-day service standard:
- Mailed on Friday: expected on Monday. Saturday and Sunday both count.
- Mailed on Saturday: expected on Wednesday. The Sunday is left out, so the count starts on Monday.
In that example, waiting from Friday to Saturday moves the expected delivery from Monday to Wednesday. When the arrival date matters, mail by Friday, and treat the day before a postal holiday the same way. When the count ends on a Sunday or a postal holiday, the Service Commitments tool shows the next delivery day.
USPS service standards for First-Class Mail in 2026#
USPS reset its service standards in two steps, on April 1 and July 1, 2025, and those are the standards in force now. The range stayed at 1–5 days. What changed is how a letter's place in that range is set:
- Standards are set by 5-digit ZIP code pair. They used to be set by the first three digits of each ZIP code. This is why a ZIP lookup gives a better answer than a rule about distance.
- Mail that stays in one region has a 2-day or 3-day standard. USPS calls this turnaround mail: a letter mailed and delivered within the same processing facility's service area.
- A letter mailed far from a regional processing center gets one more day. The extra day applies to a single letter mailed from a ZIP code more than 50 miles from that center.
Two letters travelling the same distance can therefore have different standards. USPS publishes the details on its service standard changes (opens in new tab) page.
What can make a letter arrive later than the lookup says#
Mailing after the last collection#
A letter dropped in a collection box after that day's last pickup waits for the next one. Mail before the pickup time posted on the box, or hand the letter over at a Post Office counter.
An address the sorting machines can't read#
Write the complete address, including the apartment or suite number, in dark ink on a light background so USPS can read it clearly. An incomplete or incorrect address can prevent delivery. If USPS returns the letter, correct the address before mailing it again.
A recipient who has moved#
For ordinary First-Class Mail without a special handling endorsement, when a change-of-address order is on file, USPS forwards First-Class Mail (opens in new tab) to the new address at no charge for 12 months. The lookup uses the address on the envelope; treat forwarding as an additional source of uncertainty rather than relying on that original estimate.
Weather and service disruptions#
USPS posts weather closures and other disruptions on its service alerts page (opens in new tab). Check it before you mail anything with a deadline.
Faster USPS options when 1–5 days is too slow#
USPS sells two services with shorter delivery windows:
- Priority Mail has an estimated delivery window of 2–3 days and includes USPS Tracking. Standard Priority Mail does not guarantee the delivery date or offer a money-back delivery guarantee. Compare First-Class and Priority Mail before you pay the difference.
- Priority Mail Express (opens in new tab) offers 1–3-day service with a money-back guarantee to most U.S. addresses, subject to USPS terms and exceptions. Check the guaranteed date and acceptance cutoff for your destination before purchasing.
The Service Commitments lookup lists both services beside First-Class Mail. Check it before you pay: for some ZIP code pairs Priority Mail shows the same expected day as a First-Class letter.
Planning a letter around a deadline#
For a pay-by date, a notice period or any letter that has to arrive by a certain day:
- Check the expected date before choosing a service. Use Service Commitments with the actual origin, destination and mailing date. First-Class Mail can arrive after its expected date, so even the full 5-day window is not a deadline guarantee. If arrival must be guaranteed, check Priority Mail Express availability and terms.
- Mail before the weekend. A letter mailed on Saturday or the day before a holiday starts its count after the Sunday or holiday.
- Keep a record when the date you mailed it matters. A machine postmark shows the date USPS first processed the letter, which can be later than the day you mailed it. Ask for a free manual postmark at a Post Office counter, or buy a Certificate of Mailing.
- Use Certified Mail when you need proof of delivery. You get a mailing receipt and, with Return Receipt, a delivery record with the recipient's signature. Certified Mail travels at the speed of the mail class you buy it with, so on a First-Class letter the same 1–5 days apply. See what each tracking and receipt option shows.
Related guides#
Last verified against USPS.com on October 3, 2026: delivery window, counting rule and service standards.