The letters stayed in First-Class Mail. The parcels moved to Ground Advantage three years ago.
Every domestic class in one table
Class confusion is mostly a memory problem: people are working from a map that changed in 2023. This is the current shape of it, with the ceilings and speeds USPS itself publishes.
| Class | Shape and ceiling | Speed USPS states | Price anchor |
|---|---|---|---|
| First-Class Mail letter | Up to 3.5 oz | 1-5 days | $0.82 at 1 oz with stamps |
| Postcard | Standard-sized and rectangular | 1-5 days | $0.65 |
| First-Class Mail large envelope | Up to 13 oz, flat and flexible | 1-5 days | $1.69 at 1 oz |
| USPS Ground Advantage | Up to 70 lb, 130 in length plus girth | 2-5 days | From $7.90 at a Post Office |
| Priority Mail | Up to 70 lb, 108 in length plus girth | 2-3 days | From $11 at a Post Office |
| Priority Mail Express | Up to 70 lb, 108 in length plus girth | 1-3 days | Not captured in our price set |
| Media Mail | Up to 70 lb, 130 in length plus girth | Not stated by USPS as a day range | Restricted to the DMM 273 content list |
The three rows in the middle are where the 2023 change shows. USPS announced Ground Advantage in July 2023 and retired USPS Retail Ground, USPS Parcel Select Ground and USPS First-Class Package Service alongside it, together with the two matching return products. Anyone still shopping for first-class package postage is shopping for something that no longer exists under that name.
Letter, flat or parcel
USPS sorts by shape before it sorts by weight, and shape is a physical test rather than a category you choose. The practical version runs like this.
- Letter. Thin, rectangular, evenly thick, and light enough to stay under 3.5 oz. Machines handle these at speed, which is why they are the cheapest thing USPS carries.
- Flat, which USPS also calls a large envelope. Bigger than a letter, still uniform in thickness, still flexible enough to run through equipment, up to 13 oz. A 9x12 manila envelope with paper in it is the standard example.
- Parcel. Anything rigid, anything lumpy, anything that will not bend, and anything above the flat ceiling. Once a piece is a parcel it is priced as a package, and a bubble mailer with a phone in it is a parcel however flat it looks lying on a table.
The failure mode is always the same: a seller treats a padded mailer as a large envelope, puts stamps on it, and gets it back. The fix is to price it as what it is, which is what the table below shows for one real box.
| Carrier | Service | Price | Transit window returned |
|---|---|---|---|
| USPS | Ground Advantage | $9.91 | 8-9 business days |
| UPS | Ground | $10.31 | 2-3 business days |
| UPS | 3 Day Select | $15.13 | 5-6 business days |
| UPS | 2nd Day Air | $16.58 | 2-3 business days |
| FedEx | 2Day | $21.90 | 2-3 business days |
Worth noting what the transit column did there. USPS publishes a 2 to 5 day expectation for Ground Advantage, and the live quote on this lane came back with 8 to 9 business days attached to that same service. Published expectations and the window a carrier commits to on a given day are two different numbers, and the second one is the one printed on your quote. Ground Advantage pricing is broken down further in our Ground Advantage rate guide, and the older tier that people still search for is covered in first-class package rates.
What the change means in practice
The cheap lightweight tier did not vanish
It was folded in. Light parcels that used to move as first-class packages now move as Ground Advantage, which carries a 70 lb ceiling and a stated 2 to 5 day window, and starts at $7.90 at a Post Office counter.
Flats are cheap because machines like them
A uniform, bendy envelope runs through automation without a human touching it, and the price reflects that. The moment something inside makes the piece rigid, it drops out of that stream and the economics change completely.
Speed labels are expectations, not commitments
USPS puts 1 to 5 days on First-Class Mail and 2 to 5 on Ground Advantage. Those are service standards for the network as a whole. What matters for one shipment is the window returned against your actual ZIP pair at the moment you buy.
Mail classes, answered
Does First-Class Mail still carry packages?
No. USPS launched Ground Advantage in July 2023 and retired USPS Retail Ground, USPS Parcel Select Ground and USPS First-Class Package Service at the same time, along with the matching return products. First-Class Mail now covers letters, postcards and large envelopes only.
What is the weight limit for First-Class Mail?
USPS states 3.5 oz for letters and 13 oz for large First-Class Mail envelopes. Above 13 oz, or as soon as a piece is rigid rather than flat and flexible, it is priced as a package instead.
What is the difference between a flat and a parcel?
A flat is large, uniformly thick and bendy enough to run through USPS automation, and it tops out at 13 oz. A parcel is rigid, lumpy or heavier than that ceiling. The test is physical, not a choice you make on a form, which is why a padded mailer with an object inside is always a parcel.
How fast is First-Class Mail?
USPS publishes 1 to 5 days for First-Class Mail and 2 to 5 days for Ground Advantage packages. Those are network expectations rather than commitments on a single piece, and a live parcel quote returns the window the carrier is willing to attach to your specific ZIP pair that day.