REFERENCE
Container Loading Guide
How cargo fits inside standard ocean containers — weight distribution, loading patterns, and what to plan for before you ship.
PALLET CAPACITY
How many pallets fit? It depends on what's on them.
The honest answer is that pallet capacity varies more than most reference tables suggest. Generic guidance (10 pallets in a 20', 20 in a 40') assumes single-layer loading of standard 40-inch by 48-inch US pallets with light, stackable cargo. That's right for some shipments and wrong for many of the cargo types Conveyco handles every day.
Real-world capacity depends on:
- Pallet dimensions: US standard (40 × 48 inches), Euro (1.2m × 0.8m), industrial (1.2m × 1.0m), or custom — all yield different counts.
- Cargo weight per pallet: heavier cargo can't double-stack due to weight limits and crush risk. A pallet of 1-ton tote bags loads differently than a pallet of 20 kg bags wrapped in poly.
- Stackability: some cargo holds weight on top (boxed goods, palletized bags). Some cargo doesn't (fragile machinery, certain electronics).
- Container payload limit: dense cargo often hits the weight limit before filling the space. Light cargo cubes out before weighing out.
- Loading method: forklift access, manual loading, mechanized loading systems — each affects what configurations are practical.
Conveyco works through cargo specifications with shippers before loading. Different cargo, different math. Tell us what you're shipping and we'll work out the right configuration with you.
LOAD DISTRIBUTION
How weight should be distributed
Front-to-back balance
Concentrate weight slightly forward of center to minimize axle loading on the rear chassis axles. Heavy cargo loaded too far forward overloads the kingpin; too far back overloads the rear axles. A balanced load helps the drayage carrier stay within axle weight limits, which prevents overweight violations at port gates and weigh stations.
Side-to-side balance
Distribute weight evenly across the container's width. Lopsided loads cause the container to lean, increase damage risk during port handling, and can be flagged by terminals.
Top-to-bottom (heavy first)
Place heavier cargo on the bottom and lighter cargo on top. Stacking heavy cargo on light cargo crushes the lighter items in transit. This is especially critical for palletized loads in 40' high cube containers.
The 60/40 rule (general guide)
A common rule of thumb: aim for roughly 60% of the cargo weight in the front half of the container, 40% in the back half. This helps with axle compliance for US road transport. Actual distribution depends on your specific cargo and chassis configuration.
PALLET REQUIREMENTS
ISPM-15 compliance for international shipments
All wood pallets used for international shipments must comply with ISPM-15 (International Standards for Phytosanitary Measures No. 15). This is a global standard that prevents wood-borne pests from spreading between countries. Non-compliant pallets get cargo rejected at destination customs — every time.
What ISPM-15 requires
- Wood pallets must be heat-treated (HT) or fumigated (MB). Heat treatment is the global standard.
- Treated pallets must be stamped with the IPPC mark — visible on at least two sides.
- The IPPC mark identifies the country, treatment method, and the producer's registration number.
- Treatment must occur before the pallet enters the international shipment chain.
Common mistakes
- Using untreated wood pallets. Guaranteed cargo rejection at destination.
- Using pallets with missing or unreadable IPPC marks. Same result.
- Using damaged pallets that fail inspection.
- Assuming "looks fine" pallets meet the standard. Many don't.
- Using pallets from inside the warehouse without verifying compliance.
Non-wood alternatives
Plastic, metal, and composite pallets are exempt from ISPM-15 requirements entirely — they aren't wood. Many high-volume exporters use these alternatives to avoid heat treatment requirements. Tradeoffs include higher cost per pallet and pallet recovery logistics.
Conveyco's role
We flag pallet compliance before shipment and coordinate with shippers to ensure cargo arrives the way it left. If your loading facility isn't sure whether their pallets are compliant, ask us before loading. Catching a compliance issue at the warehouse costs hours; catching it at destination customs costs weeks and thousands of dollars.
LOADING PATTERNS
How different cargo types load
Palletized goods
- Most common configuration
- Pallets loaded floor-to-floor, parallel to container length
- Lashing or airbag dunnage in remaining gaps
- Top deck for additional pallets in high cube containers (if cargo permits stacking)
Bulk dry cargo (pulses, grain, animal feed)
- Loaded in container liner bags (poly liner installed at loading)
- Liner protects cargo from moisture and contamination
- Filled via top spout with grain stream conveyor or auger
- Maximum fill depends on container payload limit and cargo density
Bulk bags / Supersacks
- 1-tonne or 2-tonne flexible intermediate bulk containers (FIBCs)
- Stacked in container with corner protection
- Top of container may be netted to prevent shifting
- Heavy supersacks load 2-deep (front and back, single layer)
Bulk powders & liquids (in ISO tanks or with liner)
- Use ISO tank container for liquids/chemicals
- Use container with poly liner for fine powders
- Specific loading procedures vary by commodity
Drums, barrels, IBC totes
- Loaded against container walls with chocks or dunnage
- Banding straps connect rows for stability
- Heavier drums positioned over the chassis axle (back of container)
Machinery, equipment, large items
- Lashed to corner castings at four points
- Wood blocking or foam padding around the item
- May require flat rack or open top container for oversized cargo
Reefer cargo (palletized)
- DO NOT block airflow channels (top and floor)
- Pallets must not touch front or rear walls
- T-bar (channeled) floor allows under-pallet airflow
- Top of stack should leave at least 3–4 inches below ceiling
Mixed / consolidated cargo (LCL)
- Heavy items on bottom and centered
- Fragile items protected and braced
- Items separated by category and stacking compatibility
- Less control over neighbor cargo — protect for movement
MAXIMIZING SPACE
Getting the most from your container
Cubic feet vs payload tradeoff
Some cargo "cubes out" (fills the volume before hitting weight limit). Other cargo "weighs out" (hits the payload limit before filling the volume). Knowing which category your cargo falls into determines container choice.
When you cube out, switch to high cube
A 40' HC offers approximately 12% more volume than a standard 40' with the same footprint and similar weight rating. For light cargo, HC is almost always the better value.
When you weigh out, multiple containers may cost less than overweight permits
A single 40' overweight container with permits may cost more than splitting into two 20' tandem chassis loads or two 40' standard loads.
Don't optimize past your operational reality
A perfectly packed container that exceeds road weight limits costs you re-handling, transloading, or fines at port. Coordinate the operational constraints first, then optimize cargo to fit.
Who actually loads the container?
Conveyco coordinates container loading through warehouse partners, transload facilities, and origin loading sites — we don't physically load containers ourselves. The loading approach depends on where the cargo originates and the operational setup.
For exports loading at origin facilities (farms, manufacturers, warehouses), the shipper or their loading crew typically loads the container. We coordinate the equipment, schedules, and any specialty requirements (liner bags, reefer pre-trip, etc.).
For transloads at our warehouse and transload vendor partners, vendor crews handle the loading. We arrange the work, but we need cargo specifications, bracing requirements, and special handling needs communicated to us before loading begins — so the right materials and crew are in place.
The most expensive surprise in container loading is finding out at the dock that the bracing wasn't planned. We work with customers to plan the loading approach upfront.
Planning a container load?
Tell us about your cargo before you ship. We'll coordinate the right equipment, materials, and partners — and flag anything that needs special handling.