First-Class Mail days, by route
First-Class Mail is letters, cards and large envelopes (flats). Its standards, across the contiguous US:
| USPS standard | Share of routes |
|---|---|
| 2 days | 1.5% |
| 2–3 days | 2.7% |
| 3 days | 9.5% |
| 3–4 days | 15% |
| 4 days | 28% |
| 4–5 days | 11% |
| 5 days | 32% |
Share of the 814,000 pairs of three-digit ZIP areas in the contiguous US, from USPS's First-Class Mail service standards effective November 1, 2026. A range means some ZIP codes in the pair take the longer number.
Letters take longer than many people expect: the most common standard is 5 days, and even mail across town is officially 2. USPS has lengthened its letter standards on long routes since 2021, moving more mail by truck instead of plane.
Sample routes
Routes between big cities often beat the overall mix above:
| Route | Miles | USPS standard (days) |
|---|---|---|
| New York → Los Angeles | 2,460 | 5 |
| Chicago → Houston | 940 | 3 |
| Atlanta → Miami | 610 | 3 |
| Boston → Washington, DC | 390 | 3 |
| Denver → Dallas | 660 | 3 |
| Seattle → Portland, OR | 140 | 2–3 |
| Phoenix → Las Vegas | 250 | 2 |
| Minneapolis → St. Louis | 470 | 3 |
Mailing it right
The clock starts when USPS accepts the letter: drop it in a collection box before the last pickup time shown on the box, or hand it over at a Post Office counter. After the last pickup, it starts the next day. A standard 1 oz letter needs one Forever stamp; see USPS postage cost for heavier letters and large envelopes.
Tracking and proof
First-Class letters don't come with tracking. For documents that need proof of mailing or delivery, Certified Mail adds a tracked delivery record, and Priority Mail Express adds speed and a money-back guarantee.
USPS's own numbers
Days are counted from the day the carrier accepts the package (day 0), skipping Sundays and holidays. Holiday peak (mid-November to late December) can add a day or more. For a specific shipment, check the carrier's own tool.
Service information checked November 2026.
Other services
- USPS First-Class MailLetters, cards and large envelopes.
- USPS Ground AdvantageUSPS's everyday package service.
- USPS Priority MailFaster USPS packages, with Flat Rate boxes.
- USPS Priority Mail ExpressUSPS's fastest service, with a money-back guarantee.
- UPS GroundUPS's economy service, zip to zip.
- FedEx Ground and Home DeliveryFedEx's economy services, zip to zip.
Or compare every carrier at once on the delivery-time calculator.
Questions people ask
How long does a letter take to arrive?
1 to 5 business days. Under USPS's current standards, 14% of routes in the contiguous US are 3 days or less; long routes are 4–5. Sundays and holidays don't count.
Is First-Class Mail delivered on Saturday?
Yes. USPS delivers letters Monday through Saturday and counts Saturday as a delivery day.
Can I mail a package by First-Class Mail?
Not anymore. Since 2023, small packages go by USPS Ground Advantage. First-Class Mail is for letters, cards and large envelopes.