CBM Freight Calculator

CBM (Cubic Meter) expresses cargo volume in cubic meters and is the basis for sea-freight rates. Volumetric weight converts volume into an equivalent weight for air freight, so bulky-but-light shipments are billed fairly. Carriers typically bill on whichever is larger — actual weight or volumetric weight.

Enter length, width, height and quantity (number of boxes), choose the input unit (cm or m), and CBM and volumetric weight are calculated automatically.

CBM (m³) = L × W × H (m) × quantity

Volumetric weight (kg) = L × W × H (cm) ÷ 6,000 × quantity

Sea freight is usually billed by CBM (m³); air freight is usually billed by volumetric weight (kg).

Sea containers come in fixed sizes, so computing your cargo's CBM lets you roughly estimate how many will fit. Industry convention treats a 20ft container's usable capacity as about 33㎥ (CBM) and a 40ft container's as about 67㎥. These are only rough benchmarks, though — actual interior dimensions vary slightly by manufacturer and model (standard vs. high-cube), so the exact loadable quantity depends on cargo shape and stacking method too.

Sea-freight rates also often use the concept of R.TON (Revenue Ton): whichever is larger between the cargo's actual weight (in tons) and its volume (in CBM) becomes the billing basis, with 1 CBM conventionally treated as 1 R.TON (roughly 1,000kg equivalent). For example, a light shipment with 5 CBM of volume but only 2 tons of weight is billed at 5 R.TON (volume basis), while a dense shipment with 1 CBM of volume but 3 tons of weight is billed at 3 R.TON (weight basis). This resembles air freight's volumetric weight (÷6,000) in spirit, but the divisor and application differ, so don't confuse the two.