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📦 CBM · CFT · Container Packing Optimizer
CBM & Container Loading Calculator
Calculate total cargo volume in cubic meters (CBM) and cubic feet (CFT). Estimate how many cartons fit in 20ft, 40ft, and High Cube containers, verifying weight and volume constraints.
Step By Step
How to Use This Calculator
6 steps
- Select your measurement units (Centimetres, Inches, or Metres) and weight unit (kg or lbs).
- Enter the length, width, and height of a single shipping carton box.
- Input the gross weight of a single carton (optional, used to check payload limits).
- Enter the total number of cartons in your shipment order.
- Select a standard container size from the dropdown (20ft Standard, 40ft Standard, 40ft High Cube, or 45ft High Cube).
- Review the total volume in CBM/CFT, total gross weight, and container volume/weight capacity utilization charts.
Worked Example
Example: Shipping 500 cartons of clothing (50 x 40 x 30 cm, 15 kg each)
Use this sample to sanity-check your inputs and understand what the final result represents.
- 1Carton CBM = (50 * 40 * 30) ÷ 1,000,000 = 0.060 CBM per carton.
- 2Total cargo CBM = 0.060 CBM × 500 cartons = 30.00 CBM.
- 3Total cargo weight = 15 kg × 500 cartons = 7,500 kg (7.5 tonnes).
- 4A standard 20ft container has a max volume of 33.2 CBM and max payload of 21,800 kg. 30.0 CBM of cargo theoretically fits (30.0 < 33.2) and weighs less than the payload limit (7.5t < 21.8t).
- 5However, realistic packing efficiency is around 85% (~28.2 CBM usable). 30 CBM of cargo will exceed a single 20ft container in real-world loading, requiring a 40ft Standard container instead.
Final Result
The shipment has a total volume of 30.0 CBM and weighs 7,500 kg. A 40ft Standard container is required due to standard cargo packing volume loss.
Methodology
CBM, CFT, and Packing Fit Formulas
This section explains the calculation logic, assumptions, and source material used to make the result more trustworthy and easier to verify.
Carton CBM (metric) = (Length cm × Width cm × Height cm) ÷ 1,000,000. Carton CBM (imperial) = (Length in × Width in × Height in × 16.387) ÷ 1,000,000. Total Volume = Carton CBM × Quantity. Total Cubic Feet (CFT) = Total CBM × 35.3147. Volumetric Weight (kg) = (Length cm × Width cm × Height cm) ÷ 5,000. Theoretical Fit = Container CBM ÷ Carton CBM. Realistic Fit (85% efficiency) = (Container CBM × 0.85) ÷ Carton CBM. Payload status compares total cargo weight against the container's maximum payload limit.
Helpful tips
- 1Containers can rarely be packed to 100% volume. Allow a 10–15% buffer for carton bulging, manual loading offsets, and pallet gaps.
- 2Always verify gross carton weights. Heavy goods (e.g. denims, metals) reach the container's maximum payload limit before filling its volume.
- 3For air cargo and express shipments, volumetric weight is used for billing if it exceeds the physical weight. Check the Volumetric Weight tab.
- 4Standard ocean containers have a payload limit of ~21.8 tonnes (20ft) and ~26.7 tonnes (40ft). Exceeding these limits can lead to custom fines and safety hazards.
Frequently Asked Questions
How do I calculate carton CBM (Cubic Meters)?+
To calculate Cubic Meters (CBM) for a shipping carton, multiply its length, width, and height in centimetres and divide by 1,000,000: CBM = (Length cm * Width cm * Height cm) / 1,000,000. If your dimensions are in inches, multiply the result by 16.387 to convert cubic inches to cubic centimetres before dividing, or use our imperial toggle to convert automatically.
What is the CBM capacity of standard shipping containers?+
Standard shipping containers have the following maximum theoretical capacities: 20ft Standard = 33.2 CBM; 40ft Standard = 67.7 CBM; 40ft High Cube (HC) = 76.4 CBM; 45ft High Cube (HC) = 86.0 CBM. However, in practice, carton shapes and manual packing restrictions reduce usable volume to about 85-90% of these theoretical limits.
What is the difference between theoretical and realistic container fit?+
Theoretical fit divides the total container volume by individual carton volume. Realistic fit accounts for packing efficiency losses (usually 10-15%) caused by cardboard bulging, stacking orientation, cargo gaps, and structural supports inside the container. Our calculator shows both theoretical limits and a realistic estimation at 85% packing efficiency.
What are the weight limit constraints for shipping containers?+
In addition to volume limits, ocean freight is constrained by legal road and port weight limits. A standard 20ft container has a max payload capacity of approximately 21,800 kg (21.8 tonnes), and a 40ft container has a payload limit of about 26,700 kg (26.7 tonnes). If your cargo consists of heavy materials, you may reach the weight limit (max payload) before filling the container's volume (CBM).
How is volumetric weight calculated for shipping cartons?+
Volumetric (or dimensional) weight is used by air freight and couriers to charge for bulky but lightweight cargo. The standard formula is: Volumetric Weight (kg) = (Length cm * Width cm * Height cm) / 5,000. If the volumetric weight is higher than the actual physical weight, shippers will bill you based on the volumetric weight.
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