The essence of container loading calculation is to answer three questions: Will it fit? Is it overweight? What is the most cost-effective way to load?
I. Quick Loading Capacity Calculation
1.1 Estimation by Volume
Loading capacity (number of cartons/units) = Internal container volume ÷ Volume per unit of cargo × Load factor
The load factor is typically between 0.75 and 0.88 (depending on how regular the cargo shape is).
Quick Reference Table:
| Container Type | Theoretical Volume | Irregular Cargo (factor 0.75) | Semi-regular Cargo (factor 0.80) | Regular Cargo (factor 0.88) |
| 20GP | 33.1 CBM | ~25 CBM | ~26 CBM | ~29 CBM |
| 40GP | 67.5 CBM | ~51 CBM | ~54 CBM | ~59 CBM |
| 40HQ | 76.0 CBM | ~57 CBM | ~61 CBM | ~67 CBM |
1.2 Estimation by Weight
Loading capacity (number of units) = Maximum container payload ÷ Weight per unit of cargo
However, due to road weight restrictions, the actual usable payload is lower:
| Container Type | Standard Maximum Payload | Usable Payload for US Trade Lanes | Usable Payload for Europe Trade Lanes |
| 20GP | 28,200 kg | ≤20,000 kg | ≤23,000 kg |
| 40GP | 28,800 kg | ≤20,000 kg | ≤23,000 kg |
| 40HQ | 28,620 kg | ≤20,000 kg | ≤23,000 kg |
1.3 Quick Determination: Volume or Weight Limit Reached First?
| Cargo Density | 1 CBM = how many kg | Limiting Factor | Strategy |
| Light/bulky cargo | <150 kg/CBM | Volume limit reached first | Choose 40HQ (largest volume) |
| Medium density | 150–350 kg/CBM | Both are close | Calculate volume first, then weight |
| Heavy cargo | >350 kg/CBM | Weight limit reached first | Choose 20GP (best payload utilization) |
II. Stowage Factor
The stowage factor is an important indicator for measuring cargo density and is used to calculate how much container volume the cargo will occupy.
Stowage Factor = Cargo volume ÷ Cargo weight (unit: m³/ton or ft³/ton)
Stowage Factors for Common Cargo
| Cargo Type | Stowage Factor (m³/ton) | Loading Suggestion |
| Steel/coiled steel | 0.3–0.5 | 20GP, weight limit reached first |
| Machinery/equipment | 1.0–2.5 | 20GP or 40GP, depending on specific dimensions |
| Furniture (knock-down) | 3.0–5.0 | 40GP or 40HQ |
| Light industrial goods in cartons | 4.0–6.0 | 40HQ, volume limit reached first |
| Plastic products | 5.0–8.0 | 40HQ is best |
| Sponge/foam | 10.0–20.0 | 40HQ, compression packing recommended |
Stowage Factor Application Example
Cargo: Plastic storage bins (carton-packed)
Total weight: 3,500 kg
Total volume: 22 CBM
Stowage factor: 22 ÷ 3.5 = 6.3 m³/ton → light/bulky cargo
Container type decision:
20GP (33.1 CBM / 6,000 kg payload limit) → Volume utilization 66%, weight utilization 58% → Wasted space
40GP (67.5 CBM / 6,000 kg payload limit) → Volume utilization 33% → Too wasteful
40HQ (76.0 CBM / 6,000 kg payload limit) → Volume utilization 29% → Too wasteful
Best solution: LCL (Less than Container Load), no need for a full container
III. Container Loading Simulation Methods
3.1 Manual Calculation Method (Most Commonly Used)
Step 1: Measure the length, width, and height of each cargo unit (accurate to cm)
Step 2: Determine the stacking orientation (which side faces down)
Step 3: Calculate how many units fit per row
Step 4: Calculate how many layers can be stacked
Step 5: Total units = Units per row × Number of rows × Number of layers
20GP Carton Loading Calculation Example:
Carton dimensions: 60 × 40 × 30 cm
Weight per carton: 15 kg
Units per row: 5,898 mm ÷ 600 mm = 9.8 → 9 units
Number of rows: 2,352 mm ÷ 400 mm = 5.8 → 5 rows
Number of layers: 2,393 mm ÷ 300 mm = 7.9 → 7 layers
Total units: 9 × 5 × 7 = 315 cartons
Total weight: 315 × 15 = 4,725 kg ✅ (far below payload limit)
Total volume: 315 × (0.6 × 0.4 × 0.3) = 22.68 CBM
Load rate: 22.68 ÷ 33.1 = 68% 🟡 Average, can be optimized
3.2 Rotation Method (Optimizing Load Rate)
If one dimension of the cargo is shorter than another, try rotating it 90 degrees and recalculate:
Orientation A: 60×40 cm face down → 9 units/row × 5 rows = 45 units/layer
Orientation B: Rotate 60×40 cm → 40×60 cm face down → 14 units/row × 3 rows = 42 units/layer
→ Orientation A is better, loading 3 more units per layer
Try at least 2–3 orientations for each calculation and choose the optimal plan.
3.3 Online Container Loading Calculation Tools
Recommended free tools (search for "container loading calculator"):
| Tool | Function | Complexity |
| SeaRates Online Calculator | Simple calculation, suitable for single-type cargo | 🟢 Simple |
| Container Calculator | Supports multiple container types | 🟡 Medium |
| EasyCargo (paid) | 3D container loading simulation, suitable for mixed cargo of multiple varieties | 🔴 Professional |
IV. Mixed Cargo Loading Calculation
When loading cargo of different specifications together, follow these steps:
Step 1: Divide cargo into heavy cargo group (>350 kg/CBM) and light cargo group (<350 kg/CBM)
Step 2: Load the heavy cargo group first (bottom 1/3)
Step 3: Load the light cargo group on top of the heavy cargo (upper 2/3)
Step 4: Calculate total weight and total volume
Step 5: Confirm that the center of gravity is within a safe range
V. Quick Loading Capacity Reference Card
The following data can be used for daily quick estimation (not precise but sufficient):
| Cargo Type | 20GP Approx. Load | 40GP Approx. Load | 40HQ Approx. Load |
| Standard pallet (1200 × 1000 mm) | 10 pcs | 21 pcs | 24 pcs |
| Standard carton (60 × 40 × 30 cm) | 300–380 cartons | 680–800 cartons | 750–880 cartons |
| Steel drum (55 gallons) | 80 drums | 168 drums | 168 drums |
| IBC tote tank | 10 units | 20 units | 20 units |
| Small machinery (1 m³ per unit) | 25 units | 60 units | 65 units |
VI. Container Loading Simulation Checklist
□ Confirm container type (20GP/40GP/40HQ/special container)
□ Measure the length, width, height, and weight of each cargo unit
□ Try at least 2 stacking orientations
□ Calculate total weight vs. payload limit
□ Calculate total volume vs. internal container volume
□ Confirm center of gravity is within safe range
□ Reserve space for dunnage and lashing (5%–10%)
□ If overweight: reduce cargo or change container type
□ If volume is insufficient: optimize arrangement or change container type
□ Draw a loading plan diagram and hand it to the loading crew
Data Note: The load factor and stowage factor are based on industry-standard calculation benchmarks. Data as of July 2026.
Need a professional loading plan? Send us the detailed dimensions and weights of your cargo, and Bofeng Logistics will help you with the optimal loading calculation to maximize loading efficiency.
Loading calculation consultation: info@zhbfwl.com
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