USPS Flat Rate service includes a priority mail flat rate for packages up to 70 lbs to any state at the same price. USPS Priority Flat rate is a shipping service provided by the US Postal Service that offers 1-3 day shipping services for a single flat rate. Flat rate service is attractive to many shippers since it essentially eliminates the need to weigh your packages in order to calculate shipping costs. As long as your package weights under 70 pounds, it can ship with USPS Priority Flat Rate service.
USPS Flat Rate Weight, Size and Shape Requirements
* Maximum weight is 70 lbs.
* Maximum combined length and girth (girth is the distance around the thickest part) is 108″.
* When sealing a Flat Rate Envelope or Box, the container flaps must be able to close within the normal folds.