A 53-foot dry van takes 26 standard 48 × 40 pallets on the floor, a 48-foot van takes 22, a 26-foot box truck takes 12, and a 40-foot container takes 18 turned or 11 straight. All of those come from the same two divisions, which is why you can redo any of them for the trailer you actually have.
The two divisions behind every number
Divide the inside length by 48, throw the remainder away, then divide the inside width by 48 and throw that remainder away too, then multiply the two whole numbers. That is the method. It needs no app and no load planner.
The remainder is where the money hides. A 53-foot van has 630 inches of floor; 13 pallets eat 624 and the six inches at the nose buy nothing. A 48-foot van is the same story with a fatter stub: 570 inches, 11 pallets, 528 used, 42 wasted. That stub is why the honest count for a 48-foot van is 22 and not the 24 you see quoted — the 24 assumes 576 inches of floor, and a van built on a 48-foot frame does not have 576 inches inside.
Why 96 inches decides the second row
Width is the number everyone skips and it decides half the answer. Two rows of 48-inch pallets need 96 inches of clear width. A 98-inch floor takes them with two inches to spare. A 100-inch floor takes them with four. A 92-inch container does not take them at all, which is the whole reason a 40-foot container gives 11 pallets one way and 18 the other.
Turning the pallet to run its 40-inch side across is not a trick you can use on every load. It needs four-way entry, because the forklift has to come in from the side, and an unnotched two-way stringer pallet will not allow it. The 40-inch side is what decides how many rows you get and how much length each pallet eats: why the 40-inch side of a GMA pallet decides whether you can load two abreast.
The floor is not the limit, the scale is
Take the payload off the door tag, subtract the empty truck, then divide by the positions you just counted. A 53-foot van rated for 45,000 pounds of freight divides to 1,731 pounds per pallet across 26 positions. A 48-foot van at 44,000 divides to 2,000 across 22. A 26-foot box truck with 10,000 pounds of payload divides to 833 across 12.
Above those numbers the count you computed is fiction. You leave with 18 pallets, an empty strip of floor you still pay for, and a scale ticket that says the truck was full. Below them the floor is the constraint and the table is the answer.
What one inch of overhang costs
A load that overhangs one inch on each side measures 50 inches, and two of those need 100 inches of clear width. On a 98-inch van the second row disappears: 13 pallets instead of 26, for cargo that grew by two inches. Measure the widest point of the load, carton or strap or corner board, not the pallet underneath it.
Checking it against your own trailer
Measure the inside from the front wall to the door, and wall to wall at the narrowest point. Do the two divisions, keep both remainders, then ask whether the spare length at the nose can take one more pallet turned sideways. On a 40-foot container it can, which is where 19 comes from instead of 18, and on a 53-foot van it cannot, which is why 26 stays 26.