Sea freight is billed on the greater of your shipment's volume in cubic meters (CBM) and its weight in metric tons — the "weight or measure" (W/M) rule, under which 1 CBM and 1,000 kg are the same billing unit, called a revenue ton. Total CBM is just length × width × height in meters, summed across pieces; compare it with the weight in tons, and the larger number is what every per-W/M rate on the quote multiplies against. Light cargo pays for the space it occupies, dense cargo pays for its mass, and nearly every LCL (less-than-container-load) invoice in the world runs on this two-line calculation.
How do you calculate CBM?
Most LCL tariffs bill a 1 CBM minimum per shipment.
A carton measuring 60 × 40 × 50 cm is 0.60 × 0.40 × 0.50 = 0.12 CBM; ten of them make 1.2 CBM. If those ten cartons weigh 650 kg (0.65 t), the shipment bills as 1.2 W/M — volume governs. Load four small crates of machine fittings instead — 0.24 CBM and 650 kg each — and you have 0.96 CBM carrying 2.6 t: the shipment bills as 2.6 W/M, weight governs. Forwarders label the unit "revenue ton," "freight ton," or just "RT"; a rate of "$95 W/M" means $95 per that greater number.
Ocean's 1,000 kg/m³ break-even is the friendliest in freight
Every mode charges by whichever of weight and volume is worth more; modes differ only in the density where the two meet. Ocean sets that point at the density of water — your cargo has to be lighter than water before volume starts governing, which is why dense industrial freight almost always bills actual tons at sea:
| Mode | Volumetric convention | Volume governs below |
|---|---|---|
| Ocean LCL | 1 CBM = 1,000 kg | 1,000 kg/m³ (62.4 lb/ft³) |
| International road groupage | 1 m³ = 333 kg (1:3,000) | 333 kg/m³ (20.8 lb/ft³) |
| Express courier | 5,000 cm³/kg | 200 kg/m³ (12.5 lb/ft³) |
| Air freight | 6,000 cm³/kg | 167 kg/m³ (10.4 lb/ft³) |
Read the table bottom-up and the classic mode migration explains itself: freight that's "all volumetric" on air chargeable weight — furniture, apparel, anything foam — gets six times more room per billed kilogram once it boards a ship. The underlying idea is the same one behind dimensional weight in domestic parcel and LTL: carriers sell space and call it weight.
Worked example: an LCL quote, line by line
Eight crates from Shanghai to Los Angeles, each 1.2 × 1.0 × 1.1 m and 260 kg:
- Volume: 1.2 × 1.0 × 1.1 = 1.32 CBM per crate → 10.56 CBM total
- Weight: 8 × 260 kg = 2,080 kg = 2.08 t
- Chargeable: max(10.56, 2.08) = 10.56 W/M
Take a mid-range 2026 base rate of $95/W/M for China → US West Coast and stack the fees the way a real quote does:
- Base ocean freight: 10.56 × $95 = $1,003
- Origin CFS/handling at $25/CBM: $264
- Destination CFS/deconsolidation at $30/CBM: $317
- Documentation, B/L and customs handling (flat): ≈ $150
Total ≈ $1,734, or about $164 per CBM — 1.7× the headline rate. That multiple is the single most useful thing to know about LCL pricing: nearly every line item scales per W/M, so the base rate is a minority of the invoice, and fuel (BAF) or peak-season surcharges can add another 20–50% on top on many lanes.
What does LCL cost in 2026?
Base port-to-port rates as of early 2026, before the fee stack above:
| Lane | Base LCL rate (USD/CBM) |
|---|---|
| China → US West Coast | $45–$160 |
| China → US East Coast | $65–$180 |
| China → Europe | $70–$150 |
| Europe → US | $65–$140 |
| India → Europe | $65–$140 |
| Intra-Asia | $40–$90 |
The ranges are wide because consolidators price by port pair, season and how full their next box is. Expect origin CFS charges of $15–$40/CBM, destination CFS of $15–$40/CBM, and per-shipment minimums around $30–$80 on individual fee lines — which is why a 0.8 CBM shipment rarely costs much less than a 2 CBM one.
When does FCL beat LCL? The 13–15 CBM break-even
FCL prices flat per container, so the comparison is your all-in LCL total versus one box. A 20ft container holds 33.2 CBM rated but loads 26–28 CBM of real cartons; a 40ft is 67.7 rated / 55–58 usable; a 40ft high cube 76.3 rated / 62–68 usable, with max payloads in the 26,460–28,180 kg range. Plan on 80–85% of rated cube.
Spot FCL rates put numbers on it. Drewry's World Container Index for September 3, 2026 assessed the composite at $4,465 per 40ft (stable week over week), with Shanghai–Los Angeles at $7,185, Shanghai–New York at $9,587 and Shanghai–Rotterdam at $4,092. Spread Rotterdam's rate across ~65 usable CBM in a high cube and the ocean leg runs ≈ $63/CBM; Shanghai–LA ≈ $111/CBM. Compare that with LCL's effective $164/CBM from the worked example — and FCL's origin/destination charges are flat per container rather than per CBM.
The practical rule: start quoting both modes at 10 CBM; the crossover typically lands at 13–15 CBM; above 15, FCL nearly always wins on price and also skips CFS handling, cuts damage-and-theft exposure, and saves the week-plus that consolidation and deconsolidation add at each end. It's the same shaped decision as LTL vs FTL domestically: past a threshold share of the vehicle, buying the whole vehicle is cheaper than renting its space by the unit.
One last hand-off: when that container lands in the US and gets transloaded to LTL for the final leg, the billing logic changes dialects — from W/M to density-based freight class. Run the same dims and weights through the freight class calculation before the domestic quote, and the numbers on your ocean B/L keep working for you all the way to the door.