How it works
CBM (Cubic Meter) is the universal metric unit of volume used across international logistics, ocean freight, air cargo, and freight forwarding. Whether you are importing inventory from overseas factories, shipping pallets via ocean freight (LCL or FCL), or fulfilling e-commerce orders, knowing your shipment’s exact cubic meter volume and volumetric weight prevents unexpected carrier surcharges and optimizes container space.
Volume per carton (m³) = Length (m) × Width (m) × Height (m) Total CBM = Volume per carton × Quantity · Total Cu Ft = Total CBM × 35.3147 Air Volumetric Weight (kg) = (Length_cm × Width_cm × Height_cm × Qty) ÷ 6,000Worked example. A shipment consists of 50 cartons, each measuring 50 cm in length, 40 cm in width, and 30 cm in height, weighing 12 kg per carton. The volume of one carton is (0.50 × 0.40 × 0.30) = 0.0600 m³. For 50 cartons, total volume is 50 × 0.0600 = 3.0000 m³ (CBM), equivalent to 105.94 cu ft. Total actual gross weight is 50 × 12 = 600.0 kg. Standard air volumetric weight (divisor 6,000) is (50 × 40 × 30 × 50) ÷ 6,000 = 500.0 kg. Because actual gross weight (600 kg) exceeds volumetric weight (500 kg), the chargeable air weight is 600.0 kg. This cargo occupies approximately 10.7% of a standard 28 m³ usable 20ft shipping container.
How to calculate CBM manually for shipping
- Measure dimensions: measure the outer length, width, and height of your packaged carton in centimeters, meters, or inches. Always measure the outermost bulges or handles.
- Convert to meters: divide centimeter dimensions by 100 (for example, 50 cm becomes 0.50 m). For inches, multiply by 0.0254.
- Multiply dimensions: multiply length by width by height to find the cubic volume of a single package.
- Multiply by carton count: multiply the single carton volume by the total number of cartons in the consignment to determine total CBM.
- Compare weight with volume: for air freight, calculate dimensional weight to know whether your shipment is charged by physical scale weight or volume.
Dimensional weight: air freight vs ocean freight
Transportation carriers charge based on whichever is greater: actual gross weight or dimensional (volumetric) weight. A lightweight box filled with feathers takes up valuable aircraft space and is billed by volume, whereas a dense box of steel bolts is billed by scale weight.
- IATA Standard Air Freight: uses a volumetric ratio of 1:6,000 cm³/kg (or 166.67 kg per CBM). Formula: (L × W × H in cm) ÷ 6,000.
- Express Courier (DHL, FedEx, UPS): frequently applies a denser divisor of 1:5,000 cm³/kg (equivalent to 200 kg per CBM).
- Ocean Freight (LCL): sea shipping applies the "Revenue Ton" rule, where 1 CBM equals 1,000 kg (1 metric ton). If your 1 CBM shipment weighs less than 1,000 kg, freight charges apply per CBM.
Standard ocean shipping container capacities
Shipping lines classify container capacities by total internal volume and practical usable volume. Real-world packing leaves empty space between cartons and pallets:
- 20ft Standard Container (20' GP): total internal volume is ~33.2 m³; practical usable cargo space is 28 m³ (holds ~10 standard pallets).
- 40ft Standard Container (40' GP): total internal volume is ~67.7 m³; practical usable cargo space is 58 m³ (holds ~20–21 standard pallets).
- 40ft High Cube Container (40' HC): total internal volume is ~76.4 m³; practical usable cargo space is 68 m³ (ideal for light, voluminous cargo).
Need to convert unit dimensions or weights? Use our unit converter. For calculating floor and warehouse storage area, open the square footage calculator, and to evaluate unit shipping costs against inventory value, consult the unit price calculator.
To compile commercial packing lists, compress customs declarations, and manage shipping manifests in secure PDF format, explore Anubis PDF.