Why stackability decides the bill
LTL carriers sell trailer space in three dimensions. A pallet that can carry another pallet on top uses only its own height; a pallet that cannot uses everything above it as well, because nothing else can go there. Carrier rules tariffs reflect that by imputing the trailer ceiling height, typically 96 inches, to units marked do-not-stack and to units over about 60 inches tall. The imputed cube is then used in cubic capacity tests such as XPO's CNWY 199 Item 233 (350 cubic feet at under 3 PCF, 750 cubic feet at under 6 PCF). The mechanics are on the 96-inch rule page.
So the question with fragile or irregular freight is not only how to protect it but whether the protection makes it stackable. A crate with a flat, rigid lid, a skeleton frame with a plywood deck on top, or a simple top cap can turn a 96-inch unit back into its real height. That costs material, labour and some added weight and cube. Whether it pays depends on the numbers.
Worked example: four units of medical carts on XPO
Four 48 × 40 pallets of assembled carts, 54 inches tall, 300 lbs each, about 950 miles on XPO. The carts have handles and uneven tops, so the shipper marks them do-not-stack. We compare three ways to ship them.
| Option | Unit dims (in) | Unit weight | Stack | Physical cube | Tariff cube | Tariff density | Class | Indicative bill |
|---|---|---|---|---|---|---|---|---|
| Pallet, do-not-stack | 48 × 40 × 54 | 300 lbs | No | 240.0 cu ft | 426.7 cu ft | 2.81 PCF | 175 | $810 |
| Pallet with plywood top cap | 48 × 40 × 56 | 320 lbs | Yes | 248.9 cu ft | 248.9 cu ft | 5.14 PCF | 175 | $401 |
| Open-frame crate | 50 × 42 × 58 | 390 lbs | Yes | 281.9 cu ft | 281.9 cu ft | 5.53 PCF | 175 | $489 |
The math for the uncrated pallets: 48 × 40 × 54 ÷ 1,728 = 60 cubic feet each, 240 for four, and 1,200 ÷ 240 = 5.00 PCF, class 175. Cubed at 96 inches each pallet is 106.67 cubic feet, 426.7 for four, and 1,200 ÷ 426.7 = 2.81 PCF. That is over 350 cubic feet at under 3 PCF, XPO's first tier, so the shipment is rated on a synthetic weight of 426.7 × 6 = 2,560 lbs instead of 1,200. On our indicative model that turns a roughly $376 class 175 bill into about $810. Carriers reissue rules tariffs; the current issue governs.
The open crate adds 2 inches to each footprint dimension, 4 inches of height and 90 lbs: 50 × 42 × 58 ÷ 1,728 = 70.49 cubic feet each, 281.9 for four, and 1,560 ÷ 281.9 = 5.53 PCF. It is stackable, so no imputation and no cube rule; still class 175, at about $489. The top cap adds 2 inches and 20 lbs per pallet: 62.22 cubic feet each, 248.9 total, 5.14 PCF, about $401.
Compare your load crated and uncrated
- Safe — tariff cube, density and linear feet stay under the carrier's cube and linear-foot rules.
- Tier 1 — 350 cu ft or more under 3 PCF (XPO, Saia, ABF, Estes): synthetic weight of 6 lbs per tariff cubic foot.
- Re-bill — 750 cu ft or more under 6 PCF, or linear feet at the carrier's rule: book volume LTL or direct partial truckload.
Does the crate pay for itself?
On freight alone the crate saves about $810 − $489 = $321 on this shipment, or about $80 per unit. A simple open frame with a plywood deck is often quoted somewhere in the $40 to $120 range per unit in materials and labour at this size; a closed plywood crate costs considerably more. So the crate roughly breaks even on freight, and the case for it rests on what else it buys: protection for the carts at two or three cross-dock touches, fewer damage claims and freight that can be double-stacked in your own warehouse.
The top cap is the clear winner on freight: about $409 less than the do-not-stack bill for a few dollars of plywood and banding per unit. It only works if the carts can genuinely carry weight through the cap. If they cannot, labelling them stackable is a damage claim waiting to happen and the carrier will deny it.
Crate and frame types compared
| Packaging | Typical added weight | Typical added size | Stackable | Best for |
|---|---|---|---|---|
| Top cap / tier sheet (plywood or heavy corrugated) | 10 to 25 lbs | 1 to 2 in height | Yes, if product carries load | Cartons and boxed goods with uneven tops |
| Pallet collar (stackable wood frame) | 15 to 40 lbs | Height in collar increments | Yes | Loose parts, irregular items |
| Open-frame (skeleton) crate | 50 to 120 lbs | 2 in per side, 3 to 5 in height | Yes | Machines, carts, fixtures |
| Closed plywood crate | 100 to 300+ lbs | 2 to 3 in per side, 4 to 6 in height | Yes | High-value, fragile, export |
These figures are indicative ranges for 48 × 40 size units and vary with lumber, design and load rating. For export moves, solid wood packaging must meet the ISPM 15 heat-treatment and marking standard. Remember that every crate adds to the measured dimensions, so write the crate's outside dimensions on the bill, not the product's; the BOL checklist covers measuring.
When crating makes density worse
Crating is not free density. It adds cube as well as weight, and on dense freight the added cube can cost a class. A 48 × 40 × 40 pallet of parts at 500 lbs is 44.44 cubic feet and 11.25 PCF, class 92.5. Crate it at 50 × 42 × 44 and 580 lbs and it becomes 53.47 cubic feet and 10.85 PCF, still class 92.5, but close to the edge; a heavier product would lose the class. Crating helps when the problem is stackability, not when the freight was already stackable and dense.
The same applies to tall freight. A crate over 60 inches tall is still likely to be cubed to 96 inches by most carriers, because a second unit will not fit above it in a standard van. If the product is 70 inches tall, a crate makes it safer but does not remove the imputation; lowering the product, shipping it laid down, or choosing a different mode does.
Crate, cap or leave it: a quick decision guide
On the dock the decision usually comes down to four questions, asked in order:
- Can the product carry weight through a flat top? If yes, add a top cap or tier sheet, label it stackable and write the new height. This is the cheapest fix and usually the biggest saving.
- Is the unit, as packed, 60 inches or less? If not, a crate will protect it but most carriers will still cube it to 96 inches. Look for ways to lower it first: lay it down, remove casters or handles, ship sub-assemblies separately.
- Is the shipment big enough to trip a cube rule? Run the tariff cube and tariff density. If a do-not-stack load stays under 350 cubic feet, or above 3 PCF on carriers with that tier, crating for rating purposes alone may not pay.
- Does the product need the protection anyway? High-value, fragile or export freight often needs a crate regardless. Then the freight saving is a bonus, and the crate design should aim for a flat, load-bearing lid.
If none of these lands cleanly, price the uncrated load on a mode that does not impute height before spending on lumber.
The mode alternative
On a direct partial truckload the freight stays on one trailer and is priced on linear feet and weight, so there is no 96-inch imputation and no cubic capacity test. For non-stackable, high-value freight such as medical equipment, switchgear or trade show exhibits, that can make crating for the carrier unnecessary, leaving only the packaging the product itself needs. See trade show crate shipping and industrial machinery freight for those cases, or send dimensions and weights to rates@cubictransport.com to price crated LTL against an uncrated partial.
