How to Load Pallets into a Container: Calculations, Diagrams, Mistakes

QUICK SUMMARY:

• A 20-foot container holds 10-11 pallets of 1200x1000mm in a single layer; a 40-foot container holds 20-23 pallets depending on the loading pattern.
• There are 3 patterns for loading pallets into a container: Block Loading (straight rows), Pinwheel Loading (diagonal rotation) and Hybrid - each optimal for different pallet sizes and goods types.
• The most common mistake is not the loading method but choosing the wrong pallet size from the start - leading to 15-25% wasted container space.
• Export pallets must comply with the ISPM 15 standard (wooden pallets) or use plastic pallets which are exempt from fumigation.
• Stretch-wrapping the goods after loading them onto the pallet is a step that cannot be skipped before loading into the container - especially for goods spending weeks at sea.

A wrongly loaded container can waste 20-30% of its volume, equivalent to millions of dong in excess shipping cost per shipment.

In 15 years advising B2B businesses in northern Vietnam on pallet and packaging solutions, I have found the biggest problem is not how goods are loaded inside the container but what happens before that: businesses choose a pallet size that does not fit the type of container they use.

The consequence is that no matter how skillfully you load, there is unavoidable wasted space. This article solves both: calculating the right pallet for the container and the most optimal way to load.

1. Container dimensions and the actual usable floor area

Before counting pallets, understand a point that is often overlooked: the container size quoted by the carrier is the external size. The actual floor area usable for loading is always significantly smaller due to the wall thickness and floor-rail structure.

Important note: For a 20DC container, the internal width of 2,352mm is the parameter that determines how pallets are loaded. This is exactly why 1200x1000mm and 1100x1100mm became the two most popular sizes for the Vietnamese domestic market - because they fit snugly within the container width under standard loading patterns. Meanwhile, a 1200x1200mm pallet does not fit two rows side by side without leaving a large gap.

2. Calculating the number of pallets in a container by actual size

This is the part most current materials handle poorly - they only state a general number without explaining how it is calculated. The basic formula is as follows, but the actual result depends on the loading pattern you choose.

For a 20-foot container (internal length 5,895mm, width 2,352mm):

The table above is calculated for a single tier of pallets.

If you stack two tiers of pallets on top of each other (double stack) - applicable only to light goods and pallets with good load capacity - the quantity doubles but you need to check that the total height does not exceed the internal height of the container.

A standard pallet is 150mm high + goods averaging 1,200mm high = 1,350mm per tier, doubled is 2,700mm - just touching the 40HC limit (2,698mm), and not usable for 40DC (2,395mm).

The cost equation: From the table above, it is clear that pallet size directly affects shipping cost. The difference from 10 pallets (block loading) to 23 pallets (pinwheel) in a 40-foot container means saving more than one container trip for every 230-pallet shipment. With current 40DC rental fees of around VND 40-60 million per trip on the Hanoi - Hai Phong port route, this is a figure well worth considering.

3. The 3 container loading patterns and when to use each

There is no single best pattern for all cases. Choosing a loading pattern depends on the pallet size, the goods type, the handling equipment at the receiving end, and the experience of the loading crew.

Pattern 1 - Block Loading (Straight rows)

All pallets are placed in the same orientation, parallel to each other. This is the simplest loading method, suitable for businesses new to container work or when goods have uneven carton sizes on the pallet.

• Advantages: Simple to execute, low risk of error, forklift access is easy from one direction.
• Disadvantages: The lowest fill rate of the 3 patterns - with 1200x1000mm pallets in a 20-foot container, only 10 pallets fit and a gap of around 700mm remains lengthwise at the end of the container. This gap cannot be used for pallets and must be filled with loose goods.

Pattern 2 - Pinwheel Loading (Diagonal rotation)

Some pallets are placed lengthwise, the rest crosswise - forming an alternating pattern that looks like a windmill. This is the most commonly used pattern in exporting consumer goods and electronics because it fills the container much better.

• Advantages: A fill rate 8-15% higher than Block Loading, significantly reducing the gap at the end of the container. With a 40-foot container and 1200x1000mm pallets, Pinwheel allows 23 pallets instead of Block Loading’s 20 - that is 3 free pallets in the same container.
• Disadvantages: The loading crew must be experienced, especially with forklifts since the access directions are no longer uniform. Some receiving ends abroad require all pallets in the same orientation for automated unloading.

Pattern 3 - Hybrid Loading (Pallets + loose goods combined)

Load pallets first into most of the container, then fit loose goods into the remaining space - usually the end corner of the container or on top of the pallets if height allows.

• Suitable for: Shipments that are mostly palletized goods but still have some loose packages that cannot be palletized (due to unusual sizes, or fragile goods needing separate packing).
• Not suitable for: Dangerous goods, food requiring strict hygiene control, or when the receiving end uses an automated unloading system.

4. Preparing the container before loading - the often-skipped step

Many businesses start loading as soon as the container is pulled into the yard without any inspection. This is a mistake with hidden major risks - especially for food, electronics or perishable goods.

A container that is damp and moldy inside, has residual chemical odor from a previous shipment, or has a cracked floor can cause total loss of the shipment after weeks at sea.

Checklist for inspecting a container before loading:

• Check for leaks: Close the container doors and stand inside - if you see light coming through the walls or roof, the container is punctured.
• Check the smell: A chemical, pesticide or strange odor is a sign of previous dangerous-goods transport. Absolutely do not use for food.
• Check the floor: A sagging, rotten or cracked floor must be rejected immediately because it cannot bear the load of a forklift driving in.
• Lashing points: Check that the steel rings on the walls are intact. Very important for heavy goods.
• Check humidity: Touch the walls; if there is condensed moisture it will create “container rain.”

Moisture-prevention solution: Use silica gel desiccant bags or desiccant sheets placed in the container before closing the doors to prevent condensation forming into a light rain inside.

5. How to load goods onto the pallet before placing it in the container

Loading goods onto the pallet correctly is a prerequisite - no matter how optimal the container loading pattern, if the goods block on the pallet is unstable, the risk still occurs.

Weight distribution principle:
Heavy goods always go on the bottom, light goods on top. The center of gravity of the entire goods block must be in the lower third to ensure the forklift does not wobble when crossing the ramp.

Ways to stack goods on a pallet:

• Brick pattern: Most recommended for export goods. Each layer rotates 90° to lock together, with excellent load resistance.
• Straight column: Stacked vertically top to bottom. Cartons bear load well but the goods block topples easily when the ship rolls sideways.
• Pyramid (Wrong): The upper layer narrows - extremely unstable, absolutely forbidden.

On load and height: Do NOT exceed the dynamic load of the pallet (because dynamic load is usually only 40-60% of static load). The maximum goods height is 1,400-1,600mm so the driver can still see the road.

6. Securing the goods after loading into the container

A sea container endures continuous 6-direction vibration - rolling lengthwise, sideways, twisting, bouncing up, pounding down. The securing step is critical.

1. Mandatory stretch-wrapping: Start from the pallet feet and wrap tightly upward. Each upper turn overlaps the lower by 50%. (Use a stretch wrapping machine to save 70% of the time for large shipments.)

2. Filling the gaps:

• Dunnage bag (air cushion): The most common, inflated with air to create excellent static pressure, and cheap.
• Thick cardboard: Stuffed into gaps temporarily for static-running goods on short legs.
• Lashing straps: For super-heavy loads, tied to the container walls.

7. Export pallet standards - mandatory conditions

Having finished packing only to have goods held at port due to wrong packaging standards is the most costly risk.

Note: Wooden pallets that once used MB (methyl bromide) chemical are now banned in the EU/US. You must choose heat-treated (HT) stamped wooden pallets. Or invest directly in export plastic pallets, which cost a bit more but never risk paperwork delays.

8. 5 mistakes businesses often make when loading pallets into a container

• ❌ Mistake 1: Choosing the wrong size. Using 1200x1200mm pallets for a 20-foot container results in only 8 pallets instead of 10-11, wasting 20% of the freight cost.
• ❌ Mistake 2: Exceeding the dynamic load. Seeing empty space and piling on goods while forgetting that when the forklift drives in, the pallet bears double the static load. The pallet cracks right inside the truck.
• ❌ Mistake 3: Not stretch-wrapping, or wrapping loosely. Thinking a snug fit is enough, but sea waves gradually shake each package down to the floor. Instead of begrudging 3 minutes, wrap really tight.
• ❌ Mistake 4: Not inserting air bags. Leaving gaps of up to 300mm for goods to collide freely.
• ❌ Mistake 5: Wooden pallets with fake ISPM 15 certification. Buying cheap but contract compensation becomes extremely expensive when the shipment is destroyed at the destination port.

9. Frequently Asked Questions

Q: How many pallets fit in a 20-foot container?
A: A 20-foot container holds 10 pallets (1200x1000mm) with Block Loading, or 11 pallets with Pinwheel Loading. With Euro pallets (1200x800mm), the figure is 11-15 pallets. Double-stacking doubles the figure (mind the height).

Q: Which pallets do not need fumigation when exporting?
A: Plastic pallets are completely exempt from fumigation. Pressed wood (LVL) pallets are also exempt because they have been heat-treated during manufacturing.

Q: Can pallets be stacked on top of each other in a container?
A: Yes, but three conditions are needed: the total height does not exceed the container; the two-tier load meets the standard; and the pallet has a stacking-corner design. Do not stack two tiers if the goods are too heavy (over 500kg).

Q: How much gap to the wall is acceptable?
A: Under 100mm with light filling is fine. From 100-300mm, use air bags. Never leave gaps over 300mm.

Conclusion

Loading pallets into a container correctly is not just a technical matter - it is a shipping-cost optimization problem. The core factors: choose the right pallet size, apply the suitable pattern, and carefully insert air bags + stretch film.

For export customs goods, always choose the safe solution such as plastic pallets to eliminate the risk of goods being returned at the destination port.

Need help with packaging advice and buying pallets? Contact ICD Vietnam now:
📍 North Vietnam: 0983 797 186 / 090 345 9186
📍 South Vietnam: 098 6784 186
✉️ Email: Sales@icdvietnam.com.vn