Bags, bales, bundles, films, and wraps are acceptable for mailing certain
easy loads and average loads. The contents in these containers should be
compressed when possible. The Postal Service does not accept such
containers for the mailing of difficult loads.
A paper bag or paper wrap is acceptable. The paper must be of at least
50-pound basis weight - the strength of a regular large grocery sack. The
contents must be immune from impact or pressure damage. The combining
(layering) of several sheets that add up to or exceed a 50-pound basis weight
is not acceptable.
A reinforced bag or a bag of at least 70-pound basis weight is acceptable. A
nonreinforced loose-fill padded bag is not acceptable as an exterior container
unless the exterior layer is of at least 60-pound basis weight.
A plastic bag - polyethylene or equivalent - used as a mailing container for
an easy load must be stretchable, must resist puncturing, must be relatively
leak-proof, and must have the following strength requirements:
• For up to 5 pounds, at least 2 mils thick.
• For up to 10 pounds, at least 4 mils thick.
Heat-shrinkable plastic film - copolymer, irradiated polyethylene, or linear
low-density polyolefin - used to form an outer mailing container must meet
the following requirements, based on load type and weight restriction:
• For an easy load of up to 5 pounds, at least 3/4 mil thick.
• For an average load of up to 5 pounds, at least 1-1/4 mils thick.
For an easy load or an average load of up to 10 pounds, a cloth bag is
acceptable if its seams are as strong as the basic material forming the bag.
If it is within postal weight limits, a bale or bundle - a large bound or
wrapped package of flat materials - is acceptable if it is adequately
compressed and reinforced to contain the contents.