In addition, the size has to be 1,728 cubic inches or less (the equivalent of 12 x 12 x 12). Your package must weigh no more than 50 pounds. UPS allows you to use your own box or mailing envelope and still take advantage of flat rate shipping. Parcels that exceed 2 cubic feet (3456 cubic inches), add $25.00. UPS Simple Rate is the term for their flat rate option.Parcels that exceed 30 inches in length, add $15.00. Order free Flat Rate boxes from the USPS.

Parcels that exceed 22 inches but not greater than 30 inches in length, add $4.00.

The planned price changes include: Priority Mail and Priority Mail Express: Commercial: 0.75 increase for PM and PME Flat Rate Boxes and Envelopes. This is one of USPS’s most utilized services, and it combines speed with reasonably economical prices, offering a good middle ground for many people who want to mail items. These temporary rates will keep USPS competitive while providing the agency with the revenue to cover extra costs in anticipation of peak-season volume. If you need something to travel more quickly, the Priority Mail service is likely to be your best option.

Parcels that exceed one cubic foot (1,728 cubic inches) are charged based on the actual weight or the dimensional weight, whichever is greater (as calculated in DMM 113.1.3). USPS Priority Mail Shipping Rates By Weight Chart.

For Sunday/Holiday delivery, add $12.50.

USPS Marketing Mail Eligibility Decision Tree.

Designing Letter and Reply Mail (PUB 25).

Usps flat rate price