Shipping Container Load Calculator
Estimate how many items fit in a 20-foot or 40-foot shipping container based on item dimensions and weight, accounting for both cube and weight limits. Use it for ocean-freight planning, supply-chain sourcing decisions, and figuring out how to consolidate inventory across containers.
Last updated: May 2026
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About this calculator
The formula computes the minimum of two constraints: items by volume = floor(container interior volume ÷ item volume), items by weight = floor(container max payload ÷ item weight); container capacity = min(by-volume, by-weight). For a 20-foot container, typical internal dimensions are roughly 230 × 92 × 95 inches (5.84 × 2.34 × 2.41 meters) ≈ 33 cubic meters / 1,170 cubic feet, with max payload around 28,000–33,000 lbs depending on container construction and shipping line limits. For a 40-foot container: roughly 472 × 92 × 95 inches ≈ 67 cubic meters / 2,365 cubic feet, max payload ~ 27,000–30,000 lbs (similar weight despite double the volume because the steel container itself weighs more). 40-foot high cube (40HC) containers are 9.5 feet tall internally vs. the standard 8.5 feet, adding ~13% more volume. Edge cases: an item too large to fit in any orientation returns zero items per container; a single item heavier than the container payload limit returns zero. The simple cube-divide method assumes perfect rectangular packing without orientation flexibility, which overestimates real capacity by 15–30% for irregular shapes; real-world cube utilization is typically 75–90% even with optimization software. The result is conservative for cubic items (boxes, crates that stack neatly) and optimistic for irregular shapes (furniture, machinery with awkward profiles). Consider whether items can be tilted, stacked, or interlocked — these often allow more units per container than naive volume-divide math suggests, but require packing planning to execute.
How to use
Example 1 — 20-foot container with mid-sized boxes. Item dimensions: 24 × 16 × 14 inches, weight 35 lbs. Container: 20' standard, internal ~ 230 × 92 × 95 inches = 2,010,200 cubic inches, max payload 33,440 lbs (the calc's assumption). Items by volume = 2,010,200 / (24×16×14) = 2,010,200 / 5376 ≈ 373. Items by weight = 33,440 / 35 ≈ 955. Capacity = min(373, 955) = 373 items, volume-constrained. Verify: items by cube fits 373; way under the weight limit. ✓ For mid-density items, cube usually wins; weight kicks in only for very dense products (metals, dense electronics, books). Example 2 — 20-foot container with heavy items. Item dimensions: 12 × 12 × 12 inches (1 cubic foot), weight 150 lbs. Items by volume = 2,010,200 / 1728 ≈ 1163. Items by weight = 33,440 / 150 ≈ 223. Capacity = min(1163, 223) = 223 items, weight-constrained. Verify: enter values into calculator and confirm. ✓ Dense items hit the weight limit long before cube. For dense goods (canned food, batteries, books, metal hardware), weight-out is typical; you can't fill the container by volume because the truck/ship axle limits cap weight. For these products, a 40-foot container often doesn't increase capacity much because weight is the binding constraint regardless of cube available.
Frequently asked questions
What are the actual interior dimensions of standard shipping containers?
A standard 20-foot container has internal dimensions of approximately 5.90 × 2.35 × 2.39 meters (232 × 92 × 94 inches), giving ~33.1 cubic meters / 1,170 cubic feet of usable volume. Max gross weight is ~24,000 kg (~52,900 lb), and max payload (cargo) is ~21,600 kg (~47,600 lb), though shipping-line limits are often lower (typically 28,000–33,000 lb cargo). A standard 40-foot container has internal dimensions ~12.0 × 2.35 × 2.39 m (472 × 92 × 94 inches), giving ~67.3 m³ / 2,378 ft³ of volume. Max gross is similar (~32,500 kg / 71,650 lb), with max payload ~26,700 kg / 58,900 lb. 40-foot high-cube containers (40HC) add 1 foot of internal height (~9 feet 6 inches), increasing volume to ~76 m³ / 2,694 ft³. Container exact dimensions vary slightly by manufacturer (Maersk, MSC, CMA-CGM, Cosco, etc.) and by construction (steel, refrigerated, open-top), so consult specific container specs for precise calculations.
What is the difference between a 20-foot and 40-foot container?
Length, weight capacity, and cost. A 40-foot container has double the volume of a 20-foot (67 m³ vs 33 m³) but only marginally more weight capacity (~27 tonnes vs 21–24 tonnes), because the container itself weighs more (about 3,750 kg for 40' vs 2,200 kg for 20') and the shipping-line and chassis axle limits cap total weight. So 40-foot containers are ideal for low-density / high-volume goods (furniture, apparel, plastics, foam products) where cube is the constraint, and 20-foot containers are often the better choice for high-density goods (metals, chemicals, dense food products) where weight hits limits first. Pricing: a 40-foot container costs roughly 1.3–1.6× a 20-foot for the same lane, making it cheaper per cubic foot for volume shipments but more expensive per ton for weight-heavy shipments. The decision usually comes down to whether your specific product is volume-constrained or weight-constrained for the shipping lane.
Why does the calculator overestimate real container capacity?
The simple volume-divide formula assumes 100% cube utilization with perfect rectangular packing — items align exactly with no gaps. Real-world container loading achieves 75–90% cube utilization at best, due to: item orientations that don't perfectly tessellate; awkward shapes that leave dead space; void fill required for shifting prevention; pallet dimensions (most cargo is palletized, and pallets occupy footprint that doesn't scale linearly with cube); fragility constraints preventing high stacking; and load-balancing requirements that limit how high or how dense one section can be. Professional container-loading software (CubeMaster, EasyCargo, etc.) can optimize stacking but rarely exceeds 90% cube utilization on real cargo. To get realistic capacity: take the simple formula result and multiply by 0.85 for cubic items, 0.70 for irregular shapes, or 0.60 for very irregular items (furniture with curves, machinery with protrusions). For high-value containerized shipping, always plan based on the realistic capacity, not the theoretical maximum.
What are the most common mistakes people make with container loading?
The biggest is using simple cube-divide math without accounting for the 75–90% real utilization rate; this overestimates capacity by 15–30%. The second is ignoring the weight limit — if you're shipping anything dense (metals, books, canned goods, batteries), weight will cap loading long before cube does, and you'll need to leave the container half-empty by volume. The third is not considering pallet vs. floor-loading; palletized cargo loses 5–10% of cube due to pallet footprint but is much faster to load/unload and easier to secure. The fourth is forgetting cargo securing requirements; loose-loaded heavy items can shift during transit, damaging cargo and the container itself, so dunnage, bracing, and air bags add to the effective volume requirement. The fifth is using a 40-foot container when a 20-foot would be cheaper for weight-constrained dense cargo; bigger isn't always cheaper per shipment. Finally, many shippers don't plan return loads or empty-container repositioning costs that can add 30–50% to one-way trade-imbalanced lanes.
When should I not use this calculator?
Skip it for non-standard containers (refrigerated, open-top, flat-rack, tank, hazmat) which have different internal dimensions, weight limits, and loading constraints; consult the specific container type's specs. It is the wrong tool for LCL (less-than-container-load) freight where you share a container with other shippers and pricing is per-cubic-meter; use an LCL rate calculator instead. Do not use it for very irregular cargo (furniture, machinery with awkward profiles, vehicles) where 3D loading optimization software is essential; manual cube-divide math overestimates capacity by 30–50% for those. It also ignores load-distribution requirements (centerline weight limits, axle-loading rules) that real shipping operations enforce. For sea freight specifically, also factor in container weighing requirements (SOLAS VGM rule requires verified gross mass declaration), customs documentation, port handling fees, and ocean-freight rates that vary substantially by trade lane and season. For high-stakes container planning, use professional 3D-loading software and consult with a freight forwarder.