Container Loading Calculator
Calculate how many cargo units fit inside a 20ft, 40ft, or 40ft HC shipping container. Use this when planning a shipment to maximize space and reduce per-unit freight costs.
About this calculator
This calculator estimates the maximum number of cargo units that can be loaded into a standard ISO shipping container by dividing the usable container volume by the volume of a single cargo unit. The three standard container types have internal volumes of approximately 33.2 m³ (20ft), 67.7 m³ (40ft), and 76.3 m³ (40ft High Cube). Because real-world loading is never perfectly efficient due to gaps, irregular shapes, and safety stacking limits, a loading efficiency percentage is applied. The formula is: Units = floor(containerVolume × loadingEfficiency / 100 ÷ (cargoLength × cargoWidth × cargoHeight)). For example, a 40ft container loaded at 85% efficiency with 0.5 m³ boxes yields floor(67.7 × 0.85 / 0.5) = 115 units. Adjusting the efficiency factor lets planners model real logistics constraints.
How to use
Suppose you are shipping boxes that are 1.0 m long, 0.5 m wide, and 0.4 m tall into a 40ft container at 85% loading efficiency. Step 1 — Box volume = 1.0 × 0.5 × 0.4 = 0.20 m³. Step 2 — Container usable volume = 67.7 × 85 / 100 = 57.545 m³. Step 3 — Units = floor(57.545 / 0.20) = floor(287.725) = 287 boxes. This means you can load 287 boxes before the container reaches practical capacity at that efficiency level.
Frequently asked questions
What is loading efficiency in a container loading calculator?
Loading efficiency is the percentage of a container's total internal volume that can realistically be filled with cargo. It accounts for dead space caused by irregular item shapes, mandatory air circulation gaps, weight distribution requirements, and packing material. A value of 100% is theoretically impossible in practice; most professional freight planners use 70–90% depending on cargo uniformity. Entering a realistic efficiency value gives you a more accurate unit count than simply dividing volumes.
How many cubic meters does a 20ft, 40ft, and 40ft HC shipping container hold?
The standard 20ft ISO container has an internal volume of approximately 33.2 m³, the 40ft standard container holds about 67.7 m³, and the 40ft High Cube (HC) offers roughly 76.3 m³ thanks to its extra 30 cm of height. These figures refer to gross internal volume; net usable volume after structural features and loading constraints is slightly lower. Always confirm exact dimensions with your carrier, as minor variations exist between manufacturers.
When should I use a container loading optimizer instead of manual calculation?
Manual calculation works fine for a single box size but quickly becomes error-prone when you have multiple SKUs, mixed pallet configurations, or weight limits to respect alongside volume. A container loading optimizer lets you model different scenarios — changing container type, adjusting efficiency, or resizing cargo — in seconds. It is especially useful for freight forwarders quoting LCL vs. FCL shipments, warehouse managers planning outbound loads, and e-commerce businesses calculating cost per unit shipped.