How the layer pattern is worked out
Fitting rectangles into a rectangle sounds trivial and is not. Laying every carton the same way often wastes a strip down one side of the pallet that is almost — but not quite — wide enough for another row.
So the calculator checks four things and keeps the best: both single orientations, and two-block patterns where part of the pallet is loaded one way and the leftover strip is loaded rotated 90 degrees. That two-block approach is what warehouse crews do by eye, and it routinely adds one or two cartons per layer over a plain grid — which compounds across every layer and every pallet in the order.
Turn off rotation if your cartons cannot be turned, because of labelling, "this way up" arrows, or a bag-in-box that only stacks in one direction.
Standard pallet sizes
| Pallet | Footprint (in) | Footprint (mm) | Deck height | Typical weight |
|---|---|---|---|---|
| GMA / North American standard | 48 × 40 | 1219 × 1016 | 5.5 in | 35–45 lb |
| Drum pallet | 48 × 48 | 1219 × 1219 | 5.5 in | ~45 lb |
| EUR1 (Euro pallet) | 47.2 × 31.5 | 1200 × 800 | 5.7 in | ~55 lb |
| EUR2 (industrial) | 47.2 × 39.4 | 1200 × 1000 | 5.7 in | ~73 lb |
The GMA 48×40 accounts for the large majority of pallets in US domestic freight. Euro pallets are narrower and will not pair two-across in a 53-foot trailer the way a 48×40 does when it is loaded 40-inch face forward.
Choosing a stack height
Common working limits are 60 inches for hand-stacked freight, 72 inches as a general default, and 84 to 96 inches where the freight is strong and the trailer allows it. Two constraints usually bite before the trailer roof does: whether the bottom cartons can carry the load above them, and whether the pallet can still be double-stacked by the carrier. A pallet built to 96 inches will never be double-stacked, which quietly doubles the trailer space it consumes — see the linear feet calculator for what that costs.
Why this feeds straight into freight class
Density is total weight divided by total cube, and both change when you change the pallet build. Add a layer and you add weight faster than you add cube, because the pallet's own 5.5 inches of dead height is already paid for. That is why a taller, fuller pallet almost always classes better than a short one, and why splitting an order across more pallets than it needs is an expensive habit.
The class shown above uses the 18-step density guideline. Run the finished figures through the freight class calculator to score them against the NMFC density sub-provision scale as well — the two disagree in several bands.