CBM & Chargeable Weight Calculator
Calculate CBM, total weight, and IATA chargeable weight for air and sea freight. Optimized for freight forwarders and exporters.
CBM (cubic metre) is the standard unit of volume for sea freight. One CBM equals a box measuring 1 m × 1 m × 1 m. Carriers charge on whichever is greater - actual weight or volumetric weight - so calculating CBM accurately is the first step in getting an honest freight quote.
For air freight, use the IATA divisor of 6,000: divide L × W × H (cm) by 6,000 to get the volumetric weight in kg. For sea LCL, 1 CBM = 1 revenue tonne (W/M - weight or measure, whichever is higher). Use this calculator to check whether your cargo pays on weight or volume, and whether it fits a 20ft or 40ft container.
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Overview & methodology
How to calculate CBM from dimensions
CBM = Length (m) × Width (m) × Height (m). If your dimensions are in centimetres, divide by 1,000,000: a carton of 120 × 80 × 100 cm = 0.96 CBM. For multiple pieces, multiply one carton's CBM by the piece count.
The W/M rule for sea LCL means you pay the higher of actual weight (per tonne) or volume (per CBM). If your cargo weighs 0.5 t but occupies 1.2 CBM, you pay on 1.2 revenue tonnes. Use the LCL/FCL breakeven tool to find the container tipping point.
Air freight chargeable weight: IATA vs integrator divisors
Airlines use 6,000 cm³/kg (IATA standard). Express integrators (DHL, FedEx, UPS) often use 5,000 cm³/kg on premium products, meaning the same box pays more. Always confirm the divisor on the quotation.
Numerical Example: Air Freight Chargeable Weight Calculation
Volumetric weight (167 kg) exceeds actual weight (100 kg) - the airline bills on 167 kg. This is typical for lightweight, bulky consumer goods.
Container utilisation and break-even
A 20ft standard container has ~33 CBM internal capacity; usable load is 25–28 CBM once cartons are stacked. The typical LCL-to-FCL switch point is around 12–14 CBM for a 20ft, but it depends on your specific LCL rate vs. FCL flat cost. See the LCL vs FCL break-even calculator for the full analysis.
Frequently asked questions
How do I calculate CBM from centimeters?
CBM = (Length × Width × Height in cm) ÷ 1,000,000. Example: 120 × 80 × 100 cm = 960,000 cm³ = 0.96 CBM. Multiply by piece count for total shipment volume.
How many CBM fit in a 20ft container?
A standard 20ft dry container has ~33 CBM internal capacity but typical utilisation is 25–28 CBM once cartons are stacked. A 40ft standard holds ~67 CBM (utilisation 54–58 CBM), and a 40ft high-cube holds ~76 CBM (~65 CBM utilised).
Is chargeable volume the same as CBM?
For sea LCL, chargeable volume is the higher of actual CBM and 1 CBM per 1,000 kg (W/M rule). For air freight, use the volumetric weight formula (L × W × H ÷ 6000 for IATA, ÷ 5000 for integrators). CBM alone is not chargeable weight.