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Home > Guides > Large package surcharge
One note first: LetterAgent labels are Canada-only Xpresspost, so this US courier fee does not apply to them. A large-package surcharge applies when a box exceeds 130 inches in length plus girth, and the carrier then bills it at a minimum 90-pound weight even if the box is nearly empty. It is the fee that turns a light, bulky box expensive.
Carriers do not use volume. They use length plus girth: take the longest side, then add twice the width plus twice the height. If that total tops 130 inches, the package is oversize. A 60-inch-long box that is 24 by 24 inches hits 156 inches and qualifies easily. The measurement includes bulges, so a box that bows outward gets measured at its widest point, not at the tape line. Shippers who measure a flat-packed box and then stuff it full are measuring the wrong thing.
| Box | Length + girth | Oversize? |
|---|---|---|
| 48 x 20 x 20 in | 48 + 80 = 128 in | No, just under |
| 60 x 24 x 24 in | 60 + 96 = 156 in | Yes |
| 36 x 30 x 30 in | 36 + 120 = 156 in | Yes, width did it |
This is the part that stings. Once a package crosses the oversize threshold, the carrier applies a minimum billable weight of 90 pounds. Your 12-pound box of pillows is priced as if it weighed 90 pounds, because on the truck and in the plane it occupies the space of 90 pounds of dense freight. Dimensional weight already penalizes bulky boxes at lower sizes; the oversize rule is the harsher version that kicks in past 130 inches. The fee is not really about weight at all. It is a space tax.
Think of additional handling as the lower tier and oversize as the upper one. Additional handling triggers at modest thresholds: 50 pounds, 48 inches long, 30 inches on the second side, or irregular packaging like tires. Oversize needs a genuinely huge box past 130 inches of length plus girth. A heavy small box draws additional handling but never oversize. A giant light box draws oversize, and possibly additional handling too if its sides cross those lower thresholds on the way up. They are separate fees that can stack on the same shipment.
Split the shipment. Two boxes under the threshold almost always cost less than one oversize box, even with two labels, because you dodge the 90-pound minimum entirely. Compress ruthlessly: vacuum bags, disassembly, and tighter packing can pull a borderline box under 130 inches. And consider freight for truly large items. Parcel carriers price oversize punitively because their networks are built for small boxes; freight carriers price by pallet space and are often cheaper once you are shipping furniture-sized goods. If the item cannot be split or compressed, freight is usually the honest answer.
Ready to ship it? Get a shipping label with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and get your label.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
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