How to Pack Pallets for Sea Freight Containers: A Stuffing Guide

Published 26 October 2026 · By Ranjeet Kumar, Proprietor, Solution Enterprises

Short answer: first make each pallet a tight, stable unit, with cartons inside the pallet edge, corners protected, straps through the pallet and film anchored to it. Then load the container so the weight is spread along its length, with about 60% of the cargo mass in no more than half the length. Fill gaps so that, in each direction, the total free space is no more than 15 cm. Load dry, use desiccants where the cargo is sensitive, and give the carrier a verified gross mass.

The figures here come from the CTU Code, the joint IMO, ILO and UNECE code of practice for packing cargo transport units. It is not mandatory, but carriers, surveyors and insurers use it as the reference for good practice, so it is the safest guide to follow.

Step 1: build a unit load that behaves as one block

• No overhang. Cartons that hang over the deck edge lose support at the corner, where the box is strongest.
• Column or interlock. Columns, with corners over corners, give the best stacking strength. Interlocking layers resist toppling better. Many shippers use columns with a tied top layer, plus strapping, to get both.
• Corner boards. Full-height boards on the four vertical edges spread strap pressure and add column strength. See stacking strength and edge protectors.
• Straps through the pallet. Strapping ties the goods to the pallet, not just to each other. Our guide to how many straps per pallet covers the count.
• Film anchored to the pallet. Stretch film must wrap the pallet itself, not stop at the bottom carton. The CTU Code warns that film alone secures cargo only if it is strong enough, and that repeated heavy loads in bad weather can fatigue it.

Step 2: check the container before you load

• Dry floor and walls, no standing water and no damp patches.
• No holes: step inside, close the doors and look for daylight.
• Clean, free of residue and smell from a previous cargo.
• Floor sound enough for the forklift, with lashing points intact.
• Payload limit on the door plate higher than your planned gross weight.

Step 3: plan the layout from inside dimensions

A standard 20 ft box is about 5,900 × 2,352 mm inside, and a 40 ft about 12,032 × 2,352 mm. Draw the pallet positions before stuffing day; our pallet sizes guide shows how many of each footprint fit and why some popular figures are optimistic.

Then place the weight. Put heavy pallets on the floor and spread them along the whole length rather than bunching them at the front or the door end. The CTU Code asks that the cargo’s centre of gravity sit close to the middle of the container’s length and width, within about 5% of length in general. Its rule of thumb is 60% of the cargo mass within 50% of the length. Terminals check this when they lift the box.

Check	Limit in the CTU Code	Why it matters
Weight along length	60% of mass within half the length	Safe lifting and handling
Centre of gravity	Within about 5% of mid-length	Spreaders can compensate only a little
Gaps	Total 15 cm or less per direction	Stops the load building speed
Mould risk	Relative humidity below 75%	Dry air prevents mould

Step 4: fill the gaps

Cargo that can move will move. The CTU Code says small gaps needed for loading and unloading are acceptable, but the total void space in any horizontal direction should not exceed 15 cm, and should be smaller still between dense cargo such as steel or stone. Options it describes:

• Dunnage bags, used strictly to the maker’s instructions for pressure and maximum gap.
• Empty pallets stood on edge and braced.
• Timber or board bracing for heavy items.

It also advises against fillers that compress permanently, such as rags or weak foam. Gaps between pallets need not be filled when the goods are firmly secured to their pallets and the pallets are stowed tightly and cannot tip. The last row at the door needs securing so nothing falls when the doors are opened.

Step 5: keep moisture out

The CTU Code notes that even dry pallets, dunnage and packing hold about 12–15% moisture, enough to bring the air in a closed container to 60–75% relative humidity. As the box cools, water condenses on the roof and drips. Its advice is to avoid wet timber, pallets and packaging, and to use desiccants together with sealed plastic wrapping for sensitive cargo. In the monsoon, load under cover. Paper packaging, including paper pallets, needs this most; see paper pallets and humidity.

Step 6: weigh, seal and record

The CTU Code makes the shipper responsible for determining the gross mass accurately and for passing the verified gross mass to the carrier as early as the carrier requires. Ask your forwarder which weighing method and cut-off apply at your port. Fix the seal as soon as packing is complete, record its number, photograph the load at the door before closing, and make sure the packing list matches what is inside. Our export packaging checklist covers the paperwork.

Stuffing-day checklist

1. Container inspected: dry, no daylight, clean, sound floor.
2. Pallet layout drawn from inside dimensions.
3. Every unit: no overhang, corners protected, strapped through the pallet, film anchored.
4. Heavy units on the floor, spread along the length.
5. About 60% of mass within half the length.
6. Gaps filled; total free space 15 cm or less in each direction.
7. Door row secured.
8. Desiccants placed if the cargo is sensitive.
9. Verified gross mass sent, seal number recorded, photos taken.

We make the paper angle boards, PET strap and paper pallets that go into a unit load. If you want them specified together for a lane, use the quote form.

Common questions

Is the CTU Code compulsory?

No. It is a non-mandatory code of practice, but it is the reference the industry uses, and national rules can draw on it.

Can I double-stack pallets in a container?

Only if both units together fit under the inside height with clearance and the lower unit, cartons and pallet, can carry the upper one for the whole voyage.

Is stretch film enough on its own?

For light, stable loads, sometimes. For sea freight the CTU Code cautions that film can fatigue in heavy weather, so strapping through the pallet is the safer choice.

Sources

• IMO/ILO/UNECE, Code of Practice for Packing of Cargo Transport Units (CTU Code), 2014 (MSC.1/Circ.1497) — chapters 8–11, Annex 3 and Annex 7.
• IMO, CTU Code overview page.
• Hapag-Lloyd, 20′ Standard and 40′ Standard container specifications.

Last verified: 26 October 2026. General guidance only, based on the CTU Code. Follow your carrier’s and forwarder’s instructions for your specific cargo and container.