How to Pack a Shipping Container Efficiently

A 40ft High Cube container holds about 76.4 cubic meters of usable space. In practice, the average loader fits about 60. That gap — 16 CBM of wasted air — is the difference between shipping one container and shipping two. Container packing isn't glamorous, but it's where importers with thin margins find real money.

This guide walks through how to plan a load, what tools to use, how to protect your cargo from a 30-day ocean roll, and the rules of thumb that seasoned warehouse teams rely on.

Step 1: Know your real usable space

Container nameplate dimensions are exterior. Internal usable space is always smaller. Approximate interior dimensions:

• 20ft Standard: 5.9 × 2.35 × 2.39 m ≈ 33.2 CBM
• 40ft Standard: 12.0 × 2.35 × 2.39 m ≈ 67.7 CBM
• 40ft High Cube: 12.0 × 2.35 × 2.69 m ≈ 76.4 CBM
• 45ft High Cube: 13.5 × 2.35 × 2.69 m ≈ 86.0 CBM

Aim to fill 85% of nameplate CBM with cargo. The remaining 15% disappears into pallet gaps, dunnage, irregular box shapes, and the safety clearance the doors need to close.

Step 2: Plan with a load list

Before anyone touches a forklift, lay out a load list — every SKU, its carton size, weight, and quantity. A simple spreadsheet works, but free tools like the CBM Calculator let you add rows in real time and see total CBM and container fit update live. The output should answer three questions:

• Will it fit?
• Will it be under the legal weight limit (typically 28,000 kg for a 20ft, 26,500 kg for a 40ft)?
• What's the best stacking order?

Step 3: Weight distribution and the 60/40 rule

A container has to ride on a chassis, get craned onto a ship, and pass road weight inspections. Distribute weight evenly: no more than 60% of the total weight in any one half of the floor (front-to-back or side-to-side). An off-balance container can tip a chassis at a sharp turn and will fail axle-weight checks at the port gate.

Heavy items go on the bottom and in the center of the container. Light, crushable items go on top, never under heavier cargo.

Step 4: Stack like a wall

Use the brick-laying pattern: offset every layer so vertical seams don't line up. A column of identical cartons with aligned seams will topple at the first hard brake. Offset seams act like a structural wall.

Where carton sizes don't tessellate cleanly, fill voids with smaller cartons, rolled goods or dunnage. Empty pockets allow cargo to shift, and shifting cargo is the #1 cause of damage claims.

Step 5: Secure with dunnage

• Airbags — fast and reusable, expand to fill gaps between pallets.
• Strapping — for tall stacks of light cartons.
• Foam blocks — for fragile or oddly shaped items.
• Plywood sheets — to spread point loads from machinery.
• Stretch wrap — every pallet, top to bottom, minimum 4 wraps.

Budget 2–4% of cargo value for dunnage. It always pays for itself.

Step 6: Floor planning — pallets vs floor-loading

Palletized loads are faster to handle but waste ~20% of space. A 20ft fits 10 EUR pallets (120×80) or 11 GMA pallets (120×100). Floor loading (no pallets) gives you ~20% more usable volume but takes much longer at destination unloading.

Mixed loads are common: pallets up front for stability, floor-loaded cartons at the back for the last few CBM.

Step 7: Photograph the load

Take 6+ photos as you load: empty container, half-loaded, full, doors closed, seal applied, seal number close-up. If a damage claim happens at destination, these are your evidence the goods left in good order.

Common mistakes to avoid

• Loading wet pallets — moisture causes container rain (condensation on the ceiling that drips for the entire voyage).
• Forgetting desiccant bags for hygroscopic goods (electronics, leather, paper).
• Stacking heavy on light.
• Ignoring the door clearance — the last 30 cm is not usable.
• Not weighing the container before shipping (VGM is mandatory under SOLAS).