Shipping fragile items and glassware: what USPS packaging rules say.

The Domestic Mail Manual sets the baseline for every parcel. These points come from its packaging section:¹

• Pieces must withstand normal transit and handling, fragile items must be cushioned, and contents must not shift.
• Heavy items must be braced and cushioned so they do not damage other mail, and heavy, dense items should not be packed with fragile ones unless they are carefully separated.
• The box must be large enough for the item with room for cushioning, and it must keep its integrity: it must not bend, fold, or collapse.
• Loose fill must overfill the container before it is closed.
• Tape and banding must be suitable for closing the package. Twine and cord are not allowed, because they can interfere with processing equipment.

The manual does not specify a number of inches of padding or a brand of material. Those choices are yours, and the shipping supplies guide lists the materials resellers commonly use.

The manual says handling markings such as "Fragile" must be applied only to packages containing delicate items, and gives glass and electrical appliances as examples of delicate items.¹ A marking is not a substitute for cushioning, and the packaging requirements apply whether or not the box is marked.

The manual has a stricter rule for liquids. A breakable container, including glass, that holds more than 4 fluid ounces must be triple-packaged: the inner container is cushioned with absorbent material, placed in a sealed, leakproof secondary container, and placed in a strong outer container. Containers must close with screw-on caps of at least one and one-half turns, and the outer container of a liquid shipment must be marked. A package that passes ISTA 3A testing is an alternative, and the mailer must provide the results on request.¹

That rule is about liquids. Empty glassware such as vases, drinking glasses, and decanters falls under the general requirements above. If you ship a perfume bottle, a decanter with contents, or anything else holding liquid, read the liquids section of the manual and ask USPS whether the item is mailable.

Room for cushioning is required, and a larger box can change the price. USPS Ground Advantage is priced by dimensional weight above 1 cubic foot, with nonstandard fees for pieces more than 22 inches long or more than 2 cubic feet.² The heavy items guide walks through the arithmetic. Measure the packed box, not the item, before you price shipping.

USPS says Ground Advantage includes $100 of insurance and lets you buy up to $5,000 in additional coverage.³ Whether a claim is paid depends on the carrier's terms, which this guide does not cover. For tracked shipments, eBay says to upload the tracking details.⁴

Cushioning, boxes, and postage all belong in the cost of a fragile sale. Strooply shows profit after fees and shipping for each item. Try the numbers in the eBay fee calculator, and see the shipping overview for how services are priced.