CBM calculator — cubic meters for shipping
Calculate CBM (cubic meters) for sea freight, LCL groupage, and container planning — entirely in your browser. Enter one box's dimensions in cm, inches, mm, meters, or feet, and the box count: you get the total volume, the common 1 CBM = 1,000 kg sea-freight weight, and a container fit estimate. No sign-up, no uploads.
Calculate CBM
Your volume
How it works
Three steps, all computed in this tab:
- Convert each side to meters. Millimeters are divided by 1,000, centimeters by 100, meters are used as-is, inches are multiplied by 0.0254, and feet by 0.3048.
- Multiply for volume. CBM per box = length × width × height in meters, then multiplied by the number of identical boxes for the total volume.
- Derive the freight figures. The common sea-freight chargeable weight uses 1 CBM = 1,000 kg. Container fit divides the typical usable CBM of a 20 ft / 40 ft / 40 ft high-cube container by your per-box CBM.
Worked example: a carton of 120 cm × 80 cm × 60 cm is 1.2 m × 0.8 m × 0.6 m = 0.576 CBM. Ship 10 cartons: 5.76 CBM total — about 5,760 kg equivalent at the 1 CBM = 1,000 kg rule, and a fraction of a 20 ft container's ~28 usable CBM. In inches, the same idea: 48 × 40 × 40 in → 1.2192 m × 1.016 m × 1.016 m ≈ 1.26 CBM.
When do you need a CBM calculator?
CBM is the language of freight quotes. Common situations where you need the number:
- LCL and groupage quotes. Sea freight for less-than-container loads is quoted per CBM (or per chargeable weight, whichever is greater). You need your total CBM to compare forwarder quotes at all.
- FBA and 3PL inbound plans. Amazon FBA and third- party logistics bookings ask for total volume and chargeable weight up front; CBM is the volume side of that pair.
- Container load planning. Is the shipment a full container or a shared one? Estimating how many of your cartons fit a 20 ft or 40 ft container tells you which product is cheaper.
- Air-freight volumetric checks. Air cargo bills the greater of gross weight and volumetric weight (about 1 CBM = 167 kg at the IATA 6,000 cm³/kg divisor). CBM is the volume input for that comparison too.
Limits
- Estimates, not quotes: the usable container CBM figures are planning rules of thumb, and the 1 CBM = 1,000 kg rule is a common convention — neither is a carrier commitment. Confirm both with your forwarder before booking.
- Palletization changes the volume: pallet footprint, pallet height, overhang, and strapping add real CBM that carton math cannot see. Carriers measure the packed cargo.
- Air and courier rules differ: air freight and courier dimensional-weight factors (for example the 6,000 cm³/kg IATA standard or the 5,000 cm³/kg courier rule) are covered by the Volumetric Weight Calculator, not this page.
- Not a booking or customs tool: this calculator produces a volume estimate only — no shipping label, no quote, no customs documentation.
Frequently asked questions
What is CBM in shipping?
CBM stands for cubic meter — the standard unit of volume used in freight, especially sea freight. Forwarders quote less-than- container-load (LCL) shipments per CBM (or per chargeable weight, whichever is greater). One CBM is a cube of 1 m × 1 m × 1 m.
How do I calculate CBM from centimeters or inches?
Convert each side to meters first, then multiply: CBM = length × width × height. From centimeters, divide each side by 100. From inches, multiply each side by 0.0254. From feet, multiply by 0.3048. Then multiply the per-box result by the number of identical boxes.
How many kg is 1 CBM for sea freight?
A common sea-freight rule is 1 CBM = 1,000 kg for chargeable weight — LCL rates are quoted per CBM or per 1,000 kg, whichever is higher (the “revenue ton” rule). Carriers and routes vary, so treat this as an estimate. Air freight uses a different factor (about 1 CBM = 167 kg at the IATA 6,000 cm³/kg divisor) — see the Volumetric Weight Calculator for courier and air-freight rules.
How many CBM fit in a shipping container?
A common planning rule of thumb is about 28 usable CBM for a 20 ft standard container (20GP), 58 for a 40 ft standard (40GP), and 68 for a 40 ft high cube (40HC). Theoretical capacities are higher (roughly 33, 68, and 76 CBM). The real usable figure depends on palletization, packing, and cargo shape — always confirm with your forwarder.
Is this CBM calculator free, and do you upload my numbers?
Yes, it is free, and no — nothing you type is uploaded anywhere. This is a static page: the calculation runs entirely in your browser tab, and your dimensions are never sent to a server, logged, or stored.
Why does my freight quote use a higher CBM than I calculated?
Carriers typically measure the packed, palletized cargo — the pallet footprint, pallet height, overhang, and strapping all add real volume — and they usually round up. Quotes may also bill the greater of volume and weight (the revenue-ton rule). Your carton math is the right starting point, but the forwarder's measured dimensions are what appears on the invoice.
Related tools
- Volumetric Weight Calculator — chargeable weight for courier, air, and sea shipments (DHL/FedEx/UPS 5,000, IATA 6,000, sea CBM × 1,000).
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Part of Local Toolworks. Last reviewed: 2026-08-17.