18 x 18 x 18 boxes
An 18x18x18 box holds 3.375 cubic feet, and parcel carriers bill it at 42 lb before your contents ever touch a scale. That number decides which loads belong in a cube this size, when a pallet beats a stack of parcel labels, and whether the cheapest box on this page is actually the cheapest way to ship. Here are all ten builds we stock, priced per box, math included.
All ten 18x18x18 builds, priced per box
This table divides each bundle by the pack count stated in its product title, because construction is what separates a $2.99 box from a $37.49 one. The sections below cover when each grade earns its price.
| Box | Pack | Bundle | Per box | Construction |
|---|---|---|---|---|
| ECT-32 Kraft Corrugated | 20 | $59.76 | $2.99 | Single wall |
| Multi-Depth ECT-32 Kraft | 20 | $67.59 | $3.38 | Single wall, pre-scored |
| ECT-44 Heavy-Duty Kraft | 20 | $92.73 | $4.64 | Heavy single wall |
| White ECT-32 | 20 | $96.67 | $4.83 | Single wall, white |
| ECT-48 Double Wall Kraft | 10 | $54.80 | $5.48 | Double wall |
| ECT-48 Double Wall, Hand Holes | 10 | $84.78 | $8.48 | Double wall, die-cut grips |
| ECT-71 Heavy-Duty Double Wall | 10 | $160.72 | $16.07 | Heavy double wall |
| Insulated Box Liners, foil bubble | 10 | $173.12 | $17.31 | Liner, fits inside the cube |
| V3c 350# Weather-Resistant | 10 | $203.58 | $20.36 | Weather-resistant, 350# |
| ECT-90 Triple Wall | 5 | $187.43 | $37.49 | Triple wall |
Per-box figures divide each bundle price by the pack count in the product title.
The 42 lb rule
Parcel carriers charge on whichever is greater: what a package weighs, or what it should weigh for the room it takes on a truck. The formula divides cubic inches by 139. An 18-inch cube is 5,832 cubic inches, which works out to 41.95, and carriers round up. So this box bills at 42 lb even when it leaves your dock nearly empty.
Read that in both directions. Ship 8 lb of pillows in it and you pay for 42, more than five times the actual weight. Ship 40 lb of dense goods and the rule costs you nothing, because billable and actual have converged. The cube does its best work between roughly 20 and 42 lb of contents: bulky enough to need the space, heavy enough that you are not mostly buying air. Lighter, check whether the load compresses into a smaller carton; heavier, the deciding question shifts from freight math to wall strength.
Parcel or freight: finding the breakpoint
A single 18x18x18 ships parcel without drama, with length plus girth at 90 inches, comfortably inside standard limits. The interesting question arrives when one order becomes many boxes to one address, because parcel billing climbs in fixed 42 lb steps and freight pricing does not.
| Boxes per shipment | Combined billable weight | How to ship it |
|---|---|---|
| 1 | 42 lb | Parcel |
| 4 | 168 lb | Parcel, still simple |
| 8 | 336 lb | Quote both and compare |
| 12, one full pallet | 504 lb | LTL freight, almost always |
The pallet geometry is friendly: four cubes per layer on a 40x48 deck, three layers high, roughly 54 inches of load. At that count a parcel network is moving 504 lb of billable weight one carton at a time, and a single LTL quote usually ends the debate. The working rule: from about eight boxes per destination, price both before printing labels.
Single wall or double wall
Every build in the range answers the same question: how much load can the panels take before they flex? ECT is the edge crush rating, the force a strip of board resists standing on end, and it runs from 32 to 90 across this page. At 18-inch spans, flex arrives earlier than small-box intuition suggests, so the double wall step matters more here than on compact cartons.
ECT-32 single wall, $2.99 per box
The default. The ECT-32 kraft cube 20-pack covers household goods, apparel, bedding, and mixed one-way loads. Buy it for volume, then spend the savings on stronger board for the few boxes that carry real weight.
ECT-44 heavy single wall, $4.64 per box
The ECT-44 heavy-duty 20-pack carries about 37 percent more edge crush strength than ECT-32 while staying single wall, so it cuts, folds, and stores the same. The pick for dense but liftable loads and for routes with several carrier handoffs.
ECT-48 double wall, $5.48 per box
Two fluted layers change how a box fails: mid-panel bulge and corner crush both back off sharply. The ECT-48 double wall bundle of ten is the storage-stack choice, because the bottom box in a three-high stack carries the other two for months.
ECT-71 double wall, $16.07 per box
The ECT-71 heavy-duty double wall bundle is for cargo that would destroy anything else on this page: machine parts, tile, cast metal. Loads that dense bill by the scale, so the money belongs in the box, not the label.
Above them all sits the ECT-90 triple wall at $37.49 per box in bundles of five. That is crate-replacement territory: single heavy items where the alternative is a wooden crate, and where the 42 lb floor stops mattering because contents weigh multiples of it.
The specialty builds
Multi-depth, $3.38 per box
The multi-depth ECT-32 20-pack is pre-scored so it folds down to a shorter box when a load does not need the full height. One SKU covers variable product heights, and every inch you fold away is dimensional weight you stop paying for.
Double wall with hand holes, $8.48 per box
A loaded cube is an awkward carry with no natural grip. The ECT-48 double wall build with hand holes fixes the ergonomics for warehouse moves and stairwells, and keeps heavy board where die-cut openings would weaken a lighter box.
Three narrower cases complete the range. White ECT-32, $4.83 per box, is the retail-facing option when the carton is part of the presentation. The V3c 350# weather-resistant build, $20.36 per box, handles humid routes and export legs where condensation softens standard kraft. And the foil bubble insulated liners, $17.31 each, drop inside any cube here when a load must hold temperature.
When the 18-inch cube is the wrong box
Two honest exits. If your loads never fill it, step down to the 16x16x16 boxes: that size bills at 30 lb instead of 42, so every downsized box saves 12 lb of billable weight before rates enter the picture. If the problem is one tall item rather than total volume, the 18x18x24 tall boxes keep this footprint and add six inches of height, the difference between a lamp packed upright and one wedged in diagonally.
18x18x18 box questions
How much does it cost to ship an 18x18x18 box?
Rates vary by carrier, service, and zone, but billable weight is fixed before any of that: an 18x18x18 box is 5,832 cubic inches, and at the standard 139 divisor it bills at a minimum of 42 lb. If your contents weigh less than 42 lb, you pay the dimensional figure, not the scale weight.
Should I buy single wall or double wall 18x18x18 boxes?
Single wall ECT-32 covers most household goods and mixed loads on a one-way trip. Step up to ECT-48 double wall when contents are dense, when filled boxes will sit stacked in storage for months, or when a carton has to survive more than one shipment. The gap is $2.99 to $5.48 per box, so upgrading only your heaviest loads costs little.
How many 18x18x18 boxes fit on a pallet?
Four per layer on a standard 40x48 pallet, and three layers keeps the loaded height near 54 inches, so twelve boxes per pallet is the practical figure. Once a shipment reaches eight or more boxes to one address, compare an LTL freight quote against the stack of parcel labels.
What fits in an 18x18x18 box?
It holds 3.375 cubic feet, which suits bulky, lighter items: bedding, coats, lampshades, small appliances, toys, or shoes in their boxes. Dense cargo like books belongs in a smaller carton, because a full 18-inch cube of paper weighs more than anyone should lift and more than single wall board should carry.
Corrugated ships flat and sets up in seconds. If this footprint is close but not right, the large shipping boxes range covers the 20, 22, and 24 inch sizes in the same wall grades.