Technical Information > How to calculate the amount of cargo in a shipping container?

How to calculate the amount of cargo in a shipping container?

Efficient use of a shipping container is the cornerstone of successful logistics and international transport. Accurate calculation of container capacity allows you to:

Minimize shipping costs per unit of goods
Prevent damage to goods during transport
Ensure smooth passage through customs procedures
Maximize the use of loading space (so-called “load optimization”)
Reduce the ecological footprint of transport due to fewer shipments

Incorrect calculation can lead to unused space, unexpected delays, damage to goods, or fines for overloading.

This glossary serves as a comprehensive guide to all key terms, methods, and procedures in the field of cargo optimization in container shipping.

Basic terms and calculations

Calculate Shipping Container Capacity

Definition:

Calculating container capacity means determining how much cargo (in terms of volume and weight) can be safely and efficiently loaded into a specific type of shipping container.

Key steps:

1. Measuring the internal dimensions of the container (length, width, height)

2. Calculation of internal volume (CBM)
Volume (CBM) = length (m) × width (m) × height (m)

3. Determining the dimensions and weight of individual packages/pallets

4. Calculation of cargo volume and weight

5. Estimation of the number of pieces that can be loaded

By dividing the usable volume by the volume of one package
Taking into account the load capacity (maximum permitted weight)

6. Application of the utilization coefficient
For common goods, we recommend calculating with 85–90% of the theoretical volume (real usable volume).

Important practical notes:

Always use the internal dimensions of the container – external dimensions are larger!
Take into account all packaging, pallets, filling material, or handling gaps.
For palletized goods, space utilization efficiency is usually lower than for “loose” packed goods.
Special software for loading planning (e.g., Goodloading) significantly helps optimize cargo distribution with regard to dimensions and weight.

CBM (Cubic Meter)

Definition:

CBM (Cubic Meter) is the standard unit of volumetric measurement in logistics, indicating the amount of space the cargo occupies.

CBM calculation for one package:

Conversion of dimensions to meters (e.g., 80 cm × 60 cm × 40 cm → 0.8 m × 0.6 m × 0.4 m)
Formula:

CBM = length (m) × width (m) × height (m)

Example:

Carton 0.5 m × 0.4 m × 0.3 m → 0.06 CBM
100 cartons → 6 CBM

Importance of CBM:

Key parameter for calculating shipping costs in LCL (Less than Container Load)
Basis for calculating chargeable weight (see below)
Helps compare the efficiency of using different types of containers

Typical container capacity in CBM (according to HZ CONTAINERS):

Container type	Theoretical volume (CBM)	Recommended usable volume (CBM)
20′ Standard	33	25–28
40′ Standard	66	54–58
40′ High Cube (HC)	76	65–68

Usable volume vs. Theoretical volume

Theoretical volume:

Calculated from the internal dimensions of the container.
The maximum volume that could be completely filled with regular shapes without gaps.

Usable volume:

The real volume that can be used for specific cargo.
Influenced by the shape of the packaging, pallet dimensions, filling material, handling gaps, and stacking method.

Practical rule of utilization:

For common goods: 85–90% of theoretical volume.
For regular, loosely packed goods (e.g., bags, rolls): up to 95%.
For palletized or irregular goods: 70–80%.

Table of difference between theoretical and real volume:

Type of goods	Expected volume utilization
Cartons	85–90 %
Palletized goods	75–85 %
Irregular shapes	70–80 %
Bulk/loose goods	up to 95 %

Dimensions and weight

Internal dimensions of shipping containers

Standard container dimensions:

Container type	Length (mm)	Width (mm)	Height (mm)
20′ Standard	6,058	2,438	2,591
40′ Standard	12,192	2,438	2,591
40′ High Cube	12,192	2,438	2,896
45′ High Cube	13,716	2,438	2,896

Note: Internal dimensions may be a few centimeters smaller due to the thickness of the walls and floor. Always verify the specific container specification with the carrier!

Maximum Payload

Definition:

Maximum payload indicates how heavy a load can be placed in the container without exceeding the technical limits of the container or road transport regulations.

Typical values (by type):

Container type	Maximum payload (kg)
20′ Standard	28,000 – 28,500
40′ Standard	28,000 – 28,800
40′ High Cube	28,500

Important practical notes:

In some countries, lower weight limits apply for road transport than for the container itself!
Less can be loaded into the container if the goods are heavy, even if there is free space.
Overloading is illegal and can lead to high fines or seizure of the shipment.

Chargeable Weight

Definition:

Chargeable weight is the parameter by which shipping is billed – the higher value between the two is always taken:

Actual weight of the shipment (in kg)
Volumetrically converted weight (CBM × conversion coefficient)

In sea freight (LCL):

Usually, 1 CBM = 1,000 kg.

Examples:

Shipment 3 CBM / 2,000 kg → chargeable weight 3,000 kg (volumetric weight)
Shipment 2 CBM / 3,000 kg → chargeable weight 3,000 kg (actual weight)

Attention:

For air freight, the conversion ratio is different (usually 1 CBM = 167 kg).

Loading process and optimization

Container Loading Plan

What is it?

The process of determining the optimal placement of cargo in a container with the aim of maximizing space utilization, minimizing the risk of damage, and ensuring safe transport.

Advantages of professional loading planning:

More efficient use of space (up to 10–20% more goods)
Better weight distribution (important for stability)
Reduced risk of damage to goods
Faster handling during loading and unloading

Modern tools:

Software allows you to enter the dimensions of the goods and the container, visualize the arrangement, and simulate various scenarios.
It automatically recommends the best placement or warns of unsuitable dimensions or overloading.
It allows for manual adjustments, rotating items, and exporting plans for warehouse workers.

Practical expert advice:

Always verify real internal dimensions and any anomalies (e.g., door dimensions, wall thickness).
Take into account handling space for unloading.
For irregular packaging, planning is key – poor placement can waste up to 20% of the space.

Stacking Types

Simple stacking:

All packages or pallets are oriented in the same direction.
Fast and easy, suitable for regular shapes.

Complex stacking:

Packages are rotated and combined in different ways for maximum space utilization.
Higher efficiency, but more demanding in terms of planning and handling.

Rules for stacking:

Heavy goods always at the bottom, light and fragile at the top.
Minimize gaps, but never overload the container structure.
For pressure-sensitive goods, use protective interlays.

Dunnage

Purpose of filling material:

Prevent movement of cargo during transport
Absorb shocks and vibrations
Protect against moisture (lifting goods above the container floor)
Distribute the pressure of heavy objects

Typical materials:

Wood and cardboard interlays
Inflatable bags (air bags)
Foam boards, polystyrene
Straps, nets

Attention:

When calculating capacity, you must always take into account the volume occupied by dunnage! Oversizing the filling can reduce usable space by up to 10%.

Broader context and related topics

Shipping Containers

Types of commonly used containers:

Type	Use and notes
Standard Dry	Common dry goods
High Cube (HC)	30 cm higher, bulky goods
Reefer (Refrigerated)	Temperature-sensitive goods
Open Top	Loading from above, heavy machinery
Flat Rack	Oversized cargo (machinery, vehicles)

Knowledge of the container type and dimensions is essential for efficient loading planning.

Disadvantages of Overseas Manufacturing

Complex logistics: Requires precise planning of every detail, including correct capacity calculation and documentation.
High logistical costs: A poorly utilized container means higher costs per unit of goods.
Long delivery times: Delays due to repacking, customs inspection, or poor distribution of goods.
Regulatory risks: An overloaded or incorrectly loaded container may be detained or rejected upon entry into the country.

Custom Product Importation & Customs

Data accuracy in documents: All data on volume, weight, and type of goods must correspond to physical reality.
Safety: A correctly loaded container reduces the risk of damage and facilitates customs inspection.
Minimizing delayed shipments: Consistent planning and accurate calculation help prevent unnecessary delays.

Practical tips and recommendations from practice

For every shipment, verify the real internal dimensions of the container – even small deviations can affect the capacity calculation.
Always ask the carrier about possible limitations (doors, wall thickness, atypical dimensions).
Invest in loading planning software – by “practicing” different scenarios in digital form, you will avoid mistakes during actual loading.
For goods sensitive to moisture or pressure, use the correct filling material and protective interlays.
Try to minimize free space between packages – unused volume means unnecessarily higher costs.

Correct calculation and planning of the amount of cargo in a shipping container is a vital skill for anyone who wants to effectively manage international transport. It affects not only costs but also the safety, speed, and reliability of the entire supply chain. Utilize knowledge of CBM, container dimensions, chargeable weight, and modern software tools.