Length Plus Girth

Volume is not the only way a parcel can be too big. A canoe paddle and a bass drum can have identical cubic volumes and give a courier completely different problems, so alongside dimensional weight every parcel carrier runs a second, purely geometric test: length plus girth.

Girth is measured the short way round. Stand the parcel on its longest side and run a tape around it perpendicular to that side — around the width and the height, twice each. That is $2(W + H)$. The longest side never enters the girth; it is added separately. So the combined size is $S = L + 2(W + H)$, and every carrier's size limit is stated in that single number. If you have ever wondered why a long thin tube and a squat cube can fall into the same rate category, this is why: the rule cares about the perimeter of the cross-section, not its shape or its area. A square section and a flat one with the same perimeter are treated alike, even though the square one holds far more.

Where the published thresholds sit, as of August 2026 — and these move, so read the service guide in force on your ship date. UPS treats 130 inches of length plus girth as a surcharge threshold, not a maximum. That distinction matters and is widely misread: a package above 130 in is a Large Package, which is a fee, not a refusal. The UPS maximum is 165 inches of length plus girth, and there is a separate length trigger — 96 inches on the longest side alone — that can make a package a Large Package even when its combined size is comfortable. USPS is 108 inches generally, and 130 inches for Ground Advantage at retail prices, with a 70 lb weight ceiling throughout; those figures come from the Domestic Mail Manual, which is federal regulation and freely readable. FedEx publishes its own limits and this site does not quote them — read them from the FedEx service guide directly rather than from a summary.

Two practical notes. First, the surcharge almost always comes with a minimum billable weight attached, so an oversize parcel is charged twice over: once as a fee and once as a weight floor. Second, the same rounding rule applies here as everywhere else — measure to the next whole inch or centimetre, upward, before adding anything. A parcel that computes to 129.6 inches is a 130-inch parcel, and 130 is exactly where the threshold sits.

When a package fails this test badly, the answer usually is not a better carton. It is a different network: past the parcel limits, freight moves on a bill of lading, priced by class and density rather than by size and girth, and the arithmetic on the rest of this shard takes over.