Trailer load plan: how many pallets fit and how to check axle weights

What a load plan is and when a written one is worth it

A load plan lists every pallet or piece, its weight, where it sits and the order it goes on. It also shows what the axles carry once the trailer is full. That is the whole job.

You can skip the paper for a single full pallet load that is the same every day. Write it down when:

• The freight is mixed, with heavy and light pallets on the same trailer.
• The trailer makes more than one stop, so the order matters at the second door.
• The load is close to the weight limit.

How many pallets fit in a 53-foot trailer

AAA Pallet says two pallets side by side, repeated 13 times, gives 26 pallet positions in a 53-foot trailer. That count assumes standard 48 by 40 inch pallets. The same source says some carriers turn the pallets in a pinwheel pattern to fit as many as 30. It adds that the count is not automatic. Trailer interiors vary, and the rear door opening can be narrower than the body.

Here is the arithmetic, using one dealer's published figures of about 52 ft 6 in (630 in) of floor length and about 100 in of width. These are approximate figures from one dealer, so check your own trailer's spec plate or builder sheet for its real interior size.

• Long side along the trailer: 630 / 48 = 13 rows (624 in used). 100 / 40 = 2 across. 13 x 2 = 26.
• Pallets turned: 630 / 40 = 15 rows (600 in used). 100 / 48 = 2 across. 15 x 2 = 30.

Floor space is only half of it. AAA Pallet warns that a trailer can have open space and still be near its practical or legal payload. Pallets at 2,000 lb each is 26 x 2,000 = 52,000 lb of freight. Add the empty trailer, which one dealer puts at about 15,000 lb for many 53-foot vans (check your own trailer's spec plate for its empty weight), and you are at about 67,000 lb before the tractor and fuel. Plan the weight first, then the positions.

The federal numbers

The federal rule is 23 CFR 658.17. It applies to the National System of Interstate and Defense Highways and reasonable access to it. It sets:

• 20,000 lb maximum on any one axle.
• 34,000 lb maximum on tandem axles.
• 80,000 lb maximum gross vehicle weight, unless the bridge formula allows less.

FHWA defines tandem axles as axles more than 40 inches and not more than 96 inches apart.

The bridge formula limits weight on any group of two or more consecutive axles by how far apart the outer axles are. FHWA writes it as W = 500 x (L x N / (N - 1) + 12 x N + 36), where W is the allowed weight on the group to the nearest 500 lb, L is the distance in feet between the outer axles of the group, and N is the number of axles in the group. FHWA says Congress enacted it in 1975 to limit the weight-to-length ratio of a vehicle crossing a bridge.

Two worked checks, as arithmetic examples:

• Two axles, 4 ft apart: 4 x 2 / 1 = 8, plus 24, plus 36 = 68. 68 x 500 = 34,000 lb. That is the tandem number.
• Five axles, 51 ft between the outer axles (an arithmetic example, not a real truck): 51 x 5 / 4 = 63.75, plus 60, plus 36 = 159.75. 159.75 x 500 = 79,875, which rounds to 80,000 lb.

The rule also lets two consecutive tandem sets carry 34,000 lb each if the first and last axle are 36 feet apart or more, and the total still cannot exceed 80,000 lb.

These are Interstate limits. States set their own limits on other roads, and permits can change them. Check the state, the route and the permit before you load to the edge. This is general information, not legal advice.

Where the weight goes

Think of the trailer as a plank resting on two supports: the kingpin at the front and the tandem at the back. The kingpin carries what the tractor holds up. The tandem carries the rest.

The closer a pallet sits to the tandem, the more of it the tandem carries. Illustrative arithmetic, not a real trailer: a 10,000 lb block of freight centered 234 in from the kingpin, with the tandem 468 in from the kingpin, splits 5,000 lb to each end. Move the block's center to 300 in and the kingpin share is 10,000 x (468 - 300) / 468 = 3,590 lb, so the tandem gets 6,410 lb.

Three habits follow:

• Put the heavy pallets near the middle of the trailer, not all in the nose and not all at the doors.
• Know where your tandem is set. In the same illustrative arithmetic, sliding the tandem toward the kingpin shifts load onto the tandem: moving it from 468 in to 420 in puts the kingpin share at 10,000 x (420 - 300) / 420 = 2,857 lb and the tandem at 7,143 lb. That is 733 lb more on the trailer tandem. This is simple lever arithmetic, not a sourced rule, and it does not say how far your own tandem can slide.
• On a multi-stop load, many shippers load the last stop first, as a common practice rather than a rule. Taking pallets off at stop one changes the weights at every axle for the rest of the route, so check the plan again after each drop.

The tractor's drive axles matter too. The kingpin load lands on the fifth wheel and is shared between the steer and drive axles, so a heavy nose can overload them even when the trailer tandem looks fine.

Step-by-step plan

1. List the units: pallet count, size and weight of each, and the stop each belongs to.
2. Weigh or confirm the weights. A guessed weight is the weakest number on the sheet.
3. Build the pallets. Mixed cartons go on pallets that respect your height and weight limits.
4. Sort by stop, last stop first.
5. Count positions for the pattern you will use.
6. Place the heaviest pallets near the middle, then fill toward the nose and the doors.
7. Add up the weight. Include the trailer's empty weight and the tractor's.
8. Estimate the steer, drive and trailer tandem weights. Compare each with its limit, and check the bridge formula for the longer groups.
9. Adjust: swap pallets, or move the tandem if the trailer allows it.
10. Print the sheet, hand it to the loader, and weigh the loaded truck.

Constraints that change the plan

• Stackable or not. A pallet marked do not stack takes a position by itself.
• Maximum stack weight. The bottom pallet has a limit.
• Fragile on top. Put fragile pallets where nothing rides on them.
• Hazmat. It has its own separation rules, which this guide does not cover. Follow the shipping papers.
• Multi-stop unload order. What comes off first goes on last, and nothing should have to move twice.
• Door width. A turned pattern is useless if the pallets cannot get through the rear door.

A printable load plan table

Copy this onto a sheet. One row per pallet position, in loading order from the nose.

Fill the limits from your own tractor, trailer and route. The federal numbers (20,000, 34,000 and 80,000) apply to the Interstate system only.

When a spreadsheet stops being enough

A sheet like the one above is fine for a handful of loads a day. It gets slow when the freight is mixed, the stops multiply, or you re-plan because an order changed. The load planning page shows what Cargohold's planner does: see 3D load planning.

One-page checklist

Frequently asked questions

How many pallets fit in a 53-foot trailer?

26 standard 48 by 40 inch pallets with the long side along the trailer, two across and 13 rows. Some carriers turn the pallets to fit up to 30. Confirm the count with the carrier, because interiors and rear doors vary.

What is the federal axle limit?

On the Interstate system, 20,000 lb on a single axle and 34,000 lb on tandem axles, with 80,000 lb gross, subject to the bridge formula. States and permits can set different numbers, so check the route.

What is the bridge formula?

A formula that limits the weight on any group of two or more consecutive axles by how far apart the outer axles are. W = 500 x (L x N / (N - 1) + 12 x N + 36), with L in feet, N the number of axles, and W rounded to the nearest 500 lb.

Does a load plan replace the driver's scale check?

No. A plan is an estimate built from the weights and positions you entered. A scale shows what the axles carry. Use the plan to get close, and the scale to confirm.

Can I plan mixed pallets?

Yes. Put each pallet's real weight in its row, place heavy ones near the middle, keep do-not-stack pallets by themselves, and load by stop. The table above handles mixed weights because every row carries its own number.

General information, not legal advice or a compliance check. Federal limits apply to the Interstate system. States and permits can differ, and equipment varies. Confirm weights on a scale.