How it works
- Letters - up to 3.5 oz and 11-1/2" x 6-1/8" x 1/4".
- Large envelopes - up to 13 oz and 15" x 12" x 3/4".
- Postcards - up to 6" x 4-1/4".
- Packages - Ground Advantage, Priority Mail, Priority Mail Express and Media Mail by ZIP code.
Prices come live from the USPS pricing API. Square, rigid or lumpy letters cost more - tick what applies.