How do I convert cubic meters to tons for ocean freight?

For LCL shipments, ocean carriers use a standard coefficient: 1 CBM = 1000 kg (1 metric ton). If your cargo weighs 500 kg but occupies 2 m³, freight will be calculated by volume (2 tons). If it weighs 3 tons but occupies 1 m³, it will be calculated by weight. This "1 CBM = 1000 kg" rule protects the carrier from transporting heavy, compact cargo at a cheap volumetric rate.

Can I load 15 Euro pallets into a 20ft container if I unload the cargo and stack the pallets?

If the goods themselves allow for stacking (e.g., boxes of uniform weight), yes, the volume will allow it. However, remember the weight limit! 15 loaded pallets can easily exceed the 28-ton limit, resulting in a "weigh out" long before you fill the volume.

What should I do if my cargo volume exceeds a 40’HC capacity by 2–3 m³?

Do not try to "force" it in. Your options are: Rethink the packaging (switch to flat-pack, remove unnecessary outer boxes). Order two 20ft containers (this is sometimes cheaper or comparable in price to one 40’HC plus overweight/repacking penalties). Ship the excess as a separate LCL shipment.

Does the container condition grade (IICL, CW) affect its internal volume?

Directly, no. Indirectly, yes. A CW container with multiple makeshift floor repairs may have swollen floorboards or welded metal patches on the walls that "eat up" those critical 5–10 cm, preventing the doors from closing.

Why can't a 40ft container hold twice the cargo volume of a 20ft container?

Because its internal length (12.03 m) is not exactly double the length of a 20ft container (5.9 m). Furthermore, a significant portion of the usable volume is "eaten up" by the increased tare weight, which reduces the allowable payload in kilograms.

How do I correctly calculate the volume of irregularly shaped cargo (e.g., machinery in a wooden crate)?

Use the "bounding box" method. Measure the maximum length, width, and height of the cargo, including the crate, protrusions, and securing hardware. Multiply these three values. Do not try to subtract "empty spaces" inside the crate: when planning container loading, only the external space occupied is counted.

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Shipping Container Volume: Internal Capacity Table for Different Container Types

Shipping container volume (CBM): actual cubic capacity of 20ft and 40ft boxes, pallet math, and volumetric weight calculation. Learn what "cube out" and "weigh out" mean and how to avoid loading planning errors.

The carrier's specification states the volume of a 20ft container is 33.2 m³. You happily sum up your cargo's cubic volume, hit that exact number, and then... get a loading refusal or face downtime at the terminal. Why? Because theoretical cubic capacity and actual loading capacity are two entirely different metrics.

Let's break down how shipping container volume (CBM) is actually calculated, how many pallet positions you can squeeze out of a standard box, and what "cube out" and "weigh out" mean.

Theoretical CBM vs. Actual Usable Capacity

CBM (Cubic Meter) is the standard unit of volume measurement in ocean freight. Manufacturers state the maximum theoretical volume, but in practice, you always lose 10–15% of the space.

Actual usable volume benchmarks for 2026

20’ DC (Dry Cube): Theoretical: 33.2 m³. Actual: 28–30 m³. Losses occur due to wall thickness, the door opening, and inevitable gaps between the cargo and the corrugated steel.
20’ HC (High Cube): Theoretical: 37.2 m³. Actual: 32–34 m³. This format is less common but indispensable for heavy and tall cargo: when weight limits prevent using a 40ft container, but the cargo simply won't fit vertically in a standard 20’ DC.
40’ DC: Theoretical: 67.7 m³. Actual: 58–60 m³.
40’ HC (High Cube): Theoretical: 76.3 m³. Actual: 68–70 m³. Those extra 30 cm of height often allow for double-stacking cargo, which is critical for lightweight but voluminous products (furniture, plastics, insulation materials).

Rule of Thumb: Never plan your loading "millimeter to millimeter" based on theoretical volume. Always apply a stowage factor of no more than 85–90%.

Pallet Math: How Much Will Actually Fit

Cubic volume means very little if your cargo is palletized. Here, pure geometry dictates the rules. The internal width of a standard box (~2350 mm) sets its own conditions.

For a 20ft Container

Euro pallets (1200 × 800 mm): Maximum 11 pieces. They are placed two in a row widthwise (crosswise). Will 11 pallets take up 13.2 meters of length? No, they are combined: some are placed lengthwise, some widthwise, to utilize the 5.9 m length as efficiently as possible. 12 pallets will only fit with perfect box geometry and no pallet collars, but this carries a huge risk of getting stuck during loading.
Industrial pallets (1200 × 1000 mm): Maximum 10 pieces. Placed strictly two in a row widthwise.

For a 40ft Container (DC and HC)

Euro pallets: 23–25 pieces (depending on the loading pattern and the stackability of the cargo itself).
Industrial pallets: 20–21 pieces.
Pro Tip: Using collarless pallets (flat pallets) or a "pinwheel" loading pattern (alternating pallet orientation) can squeeze out 1–2 additional spots in a 40ft box.

Cube Out vs. Weigh Out: Where Loading Ends

In ocean freight, there are two scenarios where container loading must stop. Understanding this will save your budget.

Cube Out (Volume Limit Reached)

The cargo is lightweight but voluminous (e.g., styrofoam or empty packaging). You have hit the volume ceiling (e.g., 68 m³ in a 40’HC), but are still far from the maximum gross weight. You pay for a Full Container Load (FCL), even though you could have shipped it cheaper as Less than Container Load (LCL), were it not for security or timing requirements.

Weigh Out (Weight Limit Reached)

The cargo is dense and heavy (rolled metal, tiles, liquids in bulk containers). You have loaded 28 tons into a 20ft container. The volume is only 40% full, but you cannot load any more: you will hit the maximum gross weight limit (usually 30,480 kg) or, more commonly, the axle weight limits for road transport when delivering from the port.

Hidden "Volume Eaters"

Even if you have perfectly calculated the cubic volume, these factors can ruin your plans:

T-bar Flooring in Reefers: In 20’ and 40’ RF containers, aluminum T-bar rails for air circulation raise the floor level by 50–70 mm and narrow the usable side space. A reefer's actual volume is always 10–12% less than its dry counterpart.
Protrusions and Corrugation: The wavy walls of a container eat up 5–8 cm on each side. If your cargo is wider than 2280 mm, it will catch on the corrugation, forcing manual reloading.
The Door Header Trap: Internal height is measured at the center of the container. At the door opening, the top header beam is often 3–5 cm lower. Cargo that is 2350 mm high might pass through the center of the box but physically will not fit through the door.

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