18 x 18 for envelopes or poly mailers.

Smallest package size usps. The priority mail flat rate® small box is about the same size and shape as three stacked dvd cases. How small can a usps package be? Packages can be up to 108 inches long.

If you'll be printing a mailing label, you can use that instead of a separate address label. Parcel dimensions generally, commercial parcels must measure: Usps is most often used for their flat rate shipping services, which benefits businesses that sell many.

Usps flat rate boxes are boxes with flat rates, no matter what the weight of the package is. If you’re small items that are heavy, flat rate boxes are going to be your best. 6 ⅛ x 11 ½.

Usps retail ground pieces may measure up to 130 inches in combined length and girth (but will be. The smallest box has a minimum length of 6 inches and a minimum height of 4 inches. If you need to send something smaller than these dimensions, choose the envelope.

The minimum size depends on your package. Usps has a size limit on letters and packages sent with the service, as follows: When shipping a box, the minimum dimensions are 6x3x0.25″.

They say good things come in small packages…but usps does have a minimum package size requirement! Packages can be up to 150 lbs. This guide outlines the requirements.