CBM Calculator
Cubic meters, LCL revenue tons (W/M) and container fit — as you type, no sign-up.
How to Calculate CBM
Sea freight is sold by space. CBM (cubic meter) is the unit: L × W × H in meters, multiplied by carton count. LCL (less than container load) rates are quoted per revenue ton — the greater of total CBM and total weight in tonnes, known as the W/M rule. Forwarders bill a minimum of 1.0 revenue ton, so small consignments pay for a full ton no matter how little space they take. The calculator shows both the raw W/M figure and the billed minimum.
Once your volume approaches ~15 CBM, ask your forwarder to quote a full 20’ container (FCL) — it is often cheaper than LCL at that size and your goods travel sealed. For air shipments, use the air freight chargeable weight calculator (÷6000) or the express calculator (÷5000) instead.
CBM to KG: There Is No Single Number
“How many kilos is a CBM?” is the most common question about this calculator, and it has no single answer. A cubic metre does not weigh anything — it is a volume. What changes is how many kilos each mode bills it as:
| Mode | Rule | 1 CBM bills as |
|---|---|---|
| Sea freight LCL | 1 CBM vs 1 tonne (W/M) | 1,000 kg |
| European road groupage | ÷ 3,000 | 333 kg |
| Australia Post / StarTrack cubic | ÷ 4,000 | 250 kg |
| Express couriers | ÷ 5,000 | 200 kg |
| Air cargo (IATA) | ÷ 6,000 | 167 kg |
1 CBM to KG in Sea Freight
LCL prices per revenue ton: the greater of your volume in CBM and your weight in tonnes, at 1 CBM = 1,000 kg. A 3 CBM consignment at 1.2 t pays for 3 revenue tons — volume wins. Only genuinely dense cargo bills by the scale at sea.
Almost every forwarder also applies a 1.0 revenue-ton minimum, so a 0.3 CBM consignment still pays for a full ton. The calculator above shows both the raw W/M figure and the billed minimum, because quoting the raw number understates a small shipment by more than 3×.
1 CBM to CFT and Other Unit Conversions
These are true conversions with fixed answers, unlike CBM to kg: 1 CBM = 35.3147 cubic feet, 1,000 litres, or 61,024 cubic inches. Full breakdown of every rule in CBM to kg.
CBM to Container: 20GP, 40GP and 40HQ Capacity
Nominal container volume and usable volume are different numbers. Cartons do not tessellate perfectly, pallets waste height, and doors limit loading — plan on 80–85% of nominal.
| Container | Internal dimensions (approx.) | Nominal | Realistic load | Payload limit |
|---|---|---|---|---|
| 20' GP | 5.90 × 2.35 × 2.39 m | 33 m³ | ~28 m³ | ~28 t |
| 40' GP | 12.03 × 2.35 × 2.39 m | 67 m³ | ~58 m³ | ~26 t |
| 40' HQ | 12.03 × 2.35 × 2.69 m | 76 m³ | ~68 m³ | ~26 t |
Note the payload trap: a 20' container holds less volume than a 40' but takes almost the same weight. Dense cargo (tiles, liquids, machinery) usually fills the weight limit long before the space — which is why heavy goods often ship in 20' containers and light goods in 40' HQ.
The LCL to FCL crossover
LCL is priced per revenue ton and stacks up fast; FCL is a flat box rate. The crossover typically sits around 13–15 CBM — beyond that a 20' FCL is often cheaper than the equivalent LCL charge, and your goods travel sealed rather than being consolidated and deconsolidated. Always price both when you are above 10 CBM.
Destination charges people forget
A cheap ocean freight quote is rarely the total. LCL shipments attract destination terminal handling (per CBM), a delivery-order fee, deconsolidation or CFS charges, customs clearance, and final trucking — on a small 2 CBM shipment these can exceed the ocean freight itself. Ask for an all-in landed quote, not just the sea leg, before comparing against air.
Time-sensitive freight? Compare against the air freight chargeable weight calculator (IATA ÷6,000) or read the air vs courier vs sea cost comparison.
CBM Calculator FAQ
How do I calculate CBM?+
CBM (cubic meter) = length × width × height in meters. For a carton measured in cm: L × W × H ÷ 1,000,000. Multiply by carton quantity and sum across sizes — this calculator does it as you type.
What is a revenue ton (W/M)?+
LCL sea freight charges per revenue ton: the greater of the shipment’s volume in CBM and its weight in metric tonnes (1 CBM = 1,000 kg equivalence). A 2.5 CBM / 800 kg shipment pays for 2.5 revenue tons. Almost every forwarder also applies a 1.0 revenue-ton minimum, so a 0.3 CBM consignment still pays for a full ton.
How many CBM fit in a 20ft / 40ft container?+
Nominal capacities are about 33 m³ (20GP), 67 m³ (40GP) and 76 m³ (40HQ), but real-world usable capacity after packing loss is closer to 28 / 58 / 68 m³ — the figures this calculator uses.
When is sea freight cheaper than air?+
As a rule of thumb, shipments over ~2 CBM or ~500 kg usually price better by sea LCL, but transit time is weeks instead of days. Compare your chargeable weight on the air freight calculator with the revenue tons here.