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LetterAgent labels are flat-rate Xpresspost for parcels up to 5 kg, so a parcel over that weight or over the carrier's size limits needs a different service. Oversize parcels still ship, but they are measured, weighed, and priced by their actual size and weight, and they often travel on a separate handling path.
A parcel can be oversized in two ways: too heavy, or too large. Carriers set a maximum weight for standard parcels, and a maximum length, girth, or combined length-plus-girth for the box. Exceeding either one pushes the parcel into an oversize or overlimit category, even if the other measurement is modest. A long, light item like a rolled poster tube or a fishing rod can be oversize on length alone, while a dense, compact box can be oversize on weight alone.
There is a third trigger that surprises people: dimensional weight. Carriers compare a parcel's actual weight with a weight calculated from its size, and charge on whichever is greater. A big, light box full of pillows can therefore cost more than a small, heavy box, because it takes up more room on a truck. If you are shipping something bulky but light, shrinking the box is often the cheapest move you can make.
Measure the packed, sealed box, not the item inside, and measure at the widest points, including any bulge. Length is the longest side, width the next, and height the shortest. Girth, where a carrier uses it, is twice the width plus twice the height, measured around the thickest part of the parcel. Round up rather than down: carriers re-measure at the depot, and a parcel that measures larger than its label says can be held, surcharged, or returned.
Weigh the sealed box on a bathroom scale if you do not have a parcel scale: weigh yourself holding the box, then weigh yourself alone, and subtract. It is not precise enough for a borderline parcel, but it tells you whether you are near a limit before you buy a label. For a parcel close to a carrier's maximum, a trip to a post office scale removes the guesswork.
| Oversize trigger | Example | What to do |
|---|---|---|
| Over the weight limit | A box of books that weighs more than the standard maximum | Split it into two parcels, or use an overlimit service |
| Over the length limit | A poster tube, a ski bag, a curtain rod | Check the carrier's maximum length before choosing a service |
| Large but light (dimensional weight) | A big box of pillows or stuffed toys | Use the smallest box that fits, compress where possible |
| Awkward shape | A bicycle wheel, an irregular sculpture | Box it square where you can; irregular shapes are harder to stack and sort |
Sometimes, and it is often cheaper. A box of books over the weight limit becomes two ordinary parcels when split in half, each with its own label. A multi-part item that disassembles, such as a shelving unit or a bed frame, can travel as several standard parcels instead of one oversize one. The trade-off is more labels, more tracking numbers, and a chance the parts arrive on different days, so tell the recipient to expect more than one box.
Splitting does not work for a single item that cannot be divided, like a guitar or a long mirror. For those, the oversize service is the honest route, and the price reflects the space the item takes and the manual handling it needs. Oversize parcels often bypass automated sorting and are handled by hand, which is slower but gentler on an awkward item.
Big items fail in different ways from small ones. A long box flexes in the middle and can snap at a weak point, so reinforce long boxes with extra tape along the full length and, for heavy items, a second layer of cardboard or a wooden batten inside. Corners take the most abuse, so protect them with edge guards or extra padding. If the item is heavy, a double-walled box is worth it: a single-walled box that holds fine on a shelf can burst when a heavy parcel is dropped on a corner.
Label placement matters more on a big box, since it may be carried from either end. Put the label on the largest flat side, where a scanner can reach it without flipping the box, and add a second copy of the address inside the box in case the outer label is torn off. For a very long item, a label near the middle of the longest side is easier to scan than one at an end.
Within Canada, a LetterAgent Xpresspost label covers parcels up to 5 kg: ask your AI assistant, approve the exact quoted price, pay once through Stripe, and receive the label as a PDF. If your packed box is over that weight or over the carrier's size limits, use a carrier service built for oversize parcels instead, and measure the sealed box before you buy any label.
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.
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