USPS box weight worksheet
Check whether an item fits your boxes, then compare weight calculations for standard rectangular parcels. This is not a postage quote.
Item and service
Use finished item dimensions. For each box, enter usable inside dimensions, shipping outside dimensions, and its empty weight. Allow room for padding.
Candidate boxes
Comparison
Fits means the item dimensions fit the entered usable inside dimensions in some orientation. It does not check padding, strength, mailability, maximum USPS size, destination, packaging restrictions, or service eligibility. Measure the sealed parcel for outside dimensions and packed weight before buying postage.
Rule used: USPS, Domestic Competitive Products Pricing and Mailing Standards Changes, final rule, effective July 12, 2026. For standard rectangular parcels in Priority Mail Express, Priority Mail, USPS Ground Advantage, and Parcel Select, round each outside dimension up to the next whole inch. When the resulting volume exceeds 1,728 cubic inches, dimensional weight is that volume ÷ 139, rounded up to a whole pound. Below that threshold, no dimensional weight applies. The comparison excludes Flat Rate, Cubic, nonrectangular parcels and special pricing. Verify current USPS standards and your specific rate before shipping.