The Single Product Container calculator tells you how many cartons of one SKU fit into a 20ft, 40ft, 40HC or 45HC sea container — by both volume (CBM) and payload (kg). Use it to plan FCL bookings, MOQ negotiations and price-per-piece landed cost before you commit to a PO.
Standard container internal capacity
Every ISO ocean container has a fixed internal cube and a maximum payload set by the carrier and the road regulations of the destination country. The numbers below are the industry-accepted usable averages — actual internal CBM varies a few percent between manufacturers (CIMC, Maersk, Singamas) and between dry, reefer and open-top variants. Always confirm the exact specs on your booking confirmation before sealing a final loading plan.
- 20ft Standard — ~33.2 m³ usable, up to 28,000 kg payload. Internal: 5.90 × 2.35 × 2.39 m.
- 40ft Standard — ~67.7 m³ usable, up to 26,500 kg payload. Internal: 12.03 × 2.35 × 2.39 m.
- 40ft High Cube — ~76.4 m³ usable, up to 26,500 kg payload. Internal: 12.03 × 2.35 × 2.69 m.
- 45ft High Cube — ~86.0 m³ usable, up to 27,000 kg payload. Internal: 13.55 × 2.35 × 2.69 m.
Note that road weight limits frequently bite before the container's structural payload. In the EU a 40ft loaded to 26,500 kg is rarely truckable without a special permit; most lanes cap door-to-door payload at 22,000–24,000 kg. In the US, highway weight rules typically limit a 40ft to ~19,500 kg gross over the road. Plan your purchase order quantities against the lower of the two numbers.
Volume vs payload — which limit hits first?
Light freight (apparel, foam, plastics, lampshades, empty bottles) usually fills the container by volume long before the weight limit. Heavy freight (tiles, stone, machinery, glass, batteries) tops out the payload limit while half the cubic space is still empty. This tool shows both percentages side-by-side so you can pick the right container size on the first try. For mixed shipments use the CBM Calculator, and for road consolidations use the Pallet Calculator.
A useful planning ratio is density — gross weight divided by volume, expressed in kg/m³. Anything under ~200 kg/m³ will cube out (volume limit first). Anything over ~400 kg/m³ will weigh out (payload limit first). Cargo in the 200–400 kg/m³ band is the sweet spot where a 40HC is almost perfectly utilised. Knowing the density of your SKU before you negotiate freight rates lets you push back on per-CBM quotes that secretly assume cube-out economics.
Real-world utilisation
Theoretical CBM assumes perfect cube-stacking with no wasted space. In practice you only achieve 80–90% of theoretical capacity after dunnage, pallets, door access and irregular carton sizes. A few common space killers worth budgeting for: pallet footprint (Euro 1.20 × 0.80 m or US GMA 1.22 × 1.02 m wastes 120–180 mm per row), inflatable dunnage bags between stacks, shoring timbers at the doors, and the 60–80 mm height penalty of every layer of stretch wrap. Read more in our guides on 20ft container dimensions and 40ft container dimensions.
Floor-loaded (no pallets) typically gets 92–95% of theoretical CBM. Palletised on Euro pallets drops to 78–84%. Palletised on US GMA pallets in a metric container is the worst case — often under 75% — which is why North-America-bound LCL consolidations frequently restow at origin. If your destination tolerates floor-loading and your cartons are uniform, you can save up to one container per ten on a typical FMCG programme.
Loading tips that protect both cube and cargo
- Plan layer by layer. Sketch the carton footprint on the container floor before loading. A 0.6 × 0.4 m carton fits 24 per layer in a 20ft (4 across × 6 deep) with almost zero waste.
- Stack heaviest at the bottom. Compression damage is the #1 ocean freight claim — keep total stack weight under 1.5× the rated box compression strength (ECT).
- Brace the doors. The last meter takes most of the dynamic load during ocean swell. Use airbags or timber shoring; never trust shrink wrap alone.
- Leave a thermal gap. 5–10 cm of air between cargo and the ceiling helps prevent container rain on long humid lanes (China–EU/US via the tropics).
- Photograph every stage. Empty container, mid-load, fully loaded, doors closed with seal number visible. This protects every insurance claim.
When to switch from 20ft to 40ft or 40HC
On most lanes a 40ft Standard costs only 25–35% more than a 20ft, so the breakeven is around 18–20 CBM or 17,000 kg of cargo — beyond that, the 40ft is cheaper per unit shipped. The jump from 40ft Standard to 40ft High Cube usually adds just 3–8% to the ocean rate while unlocking 13% more cube, so HC is almost always the right call for light cargo. Only switch to 45HC when (a) you have 80+ CBM of stable cargo, (b) the destination port and trucker can handle the extra length (some inland ramps in the US Midwest and parts of Asia cannot), and (c) the rate premium is under 12%. Otherwise two 40HCs are usually safer and similarly priced.