W/M stands for Weight or Measurement — the billing basis used for ocean LCL (Less than Container Load) freight. Carriers charge per revenue ton, using whichever is greater: your cargo's actual weight in metric tonnes or its volume in cubic metres (CBM). One revenue ton equals either 1,000 kg or 1 CBM. If your 2 CBM shipment weighs 800 kg (0.8 tonnes), you're billed for 2 revenue tons. If it weighs 2,500 kg (2.5 tonnes), you're billed for 2.5 revenue tons.
What Is W/M in a Freight Quote?
When you receive an LCL freight quote showing a rate like "$28 per W/M" or "$35 per revenue ton", the carrier is quoting on a W/M basis. The rate applies to whichever unit of measure results in the higher charge — your cargo's weight (in metric tonnes) or its volume (in CBM). This is the universal standard for ocean LCL pricing worldwide.
The logic is the same as air freight's volumetric weight concept but with different numbers: ocean carriers charge based on how much of the container you effectively occupy, whether measured by weight or by space.
In most LCL shipments, CBM tends to win because most cargo is not dense enough to make 1 tonne per CBM. The break-even density is 1,000 kg per CBM — that's extremely dense cargo like steel, glass tiles, or heavy machinery. Typical consumer goods are 200–500 kg/m³, so volume almost always wins in W/M billing.
How W/M Is Calculated — The Formula
Revenue Tons = max(weight in tonnes, volume in CBM)
Then multiply the revenue tons by the freight rate per W/M:
Freight Cost = Revenue Tons × Rate per W/M
Example 1: CBM Wins
- Cargo: 2 CBM, actual weight 500 kg (0.5 tonnes)
- Revenue tons: max(0.5, 2.0) = 2.0
- Rate: $30/W/M
- Freight cost: 2.0 × $30 = $60
Example 2: Weight Wins
- Cargo: 2 CBM, actual weight 2,500 kg (2.5 tonnes)
- Revenue tons: max(2.5, 2.0) = 2.5
- Rate: $30/W/M
- Freight cost: 2.5 × $30 = $75
Worked Example: W/M Calculation for a Real LCL Shipment
A small furniture exporter is shipping 3 SKUs from Shanghai to Rotterdam. Here's how the W/M calculation works in practice:
| SKU | Dimensions (cm) | CBM each | Qty | Total CBM | Weight (kg) | Total Weight |
|---|---|---|---|---|---|---|
| Coffee table | 110 × 60 × 50 | 0.330 | 10 | 3.30 | 18 kg | 180 kg |
| Side table | 60 × 40 × 45 | 0.108 | 20 | 2.16 | 8 kg | 160 kg |
| Bookshelf | 80 × 30 × 180 | 0.432 | 5 | 2.16 | 22 kg | 110 kg |
| Total | 7.62 CBM | 450 kg (0.45 T) |
Revenue tons: max(0.45 tonnes, 7.62 CBM) = 7.62 revenue tons (CBM wins)
At a rate of $45/W/M: 7.62 × $45 = $342.90 ocean freight
Without understanding W/M, this importer might have budgeted on weight alone: 0.45 × $45 = $20.25. They would have been invoiced 17× more than expected.
W/M vs Air Freight Divisors — How They Differ
Understanding the difference between LCL W/M and air freight volumetric weight prevents costly mode-of-transport miscalculations:
| Mode | Billing Basis | Equivalence | Break-even Density |
|---|---|---|---|
| Ocean LCL (W/M) | Higher of 1 tonne or 1 CBM | 1 CBM = 1,000 kg | 1,000 kg/m³ (very dense) |
| Air Freight (IATA ÷6,000) | Higher of actual or volumetric | 1 CBM = 167 kg | 167 kg/m³ (typical cargo) |
| Courier (÷5,000) | Higher of actual or volumetric | 1 CBM = 200 kg | 200 kg/m³ |
The key takeaway: LCL's break-even density (1,000 kg/m³) is much higher than air freight's (167 kg/m³). Almost all cargo in an LCL shipment will be charged on CBM, not weight. In air freight, cargo denser than 167 kg/m³ (metals, glass, dense machinery) will be charged on actual weight instead.
When Does Weight Win vs CBM in W/M Billing?
Weight wins in W/M billing only when your cargo density exceeds 1,000 kg per CBM. In practice, this means:
Weight Usually Wins (Dense Cargo)
- Steel and metal components
- Heavy machinery and engines
- Ceramic and porcelain products (tiles, sanitary ware)
- Glass and stone
- Batteries and electrical components with heavy housings
CBM Usually Wins (Light/Bulky Cargo)
- Furniture and wooden products
- Plastic goods and packaging
- Foam, textiles, garments
- Paper and cardboard products
- Most consumer goods (electronics, toys, household items)
If you're unsure, calculate both: divide total weight in kg by 1,000 to get tonne-equivalent, and compare to your total CBM. Whichever is larger determines your freight cost.
Frequently Asked Questions
Does W/M apply to FCL shipments?
No. FCL (Full Container Load) shipments are priced on a per-container basis, not per W/M. You pay a flat rate for the container regardless of weight or volume (subject to weight limits). W/M billing is specific to LCL (Less than Container Load) shipments where you share a container with other cargo.
What does "1 W/M" mean exactly?
One W/M unit = one revenue ton = either 1 metric tonne (1,000 kg) of actual weight OR 1 CBM of volume, whichever is greater. A rate of "$30 per W/M" means $30 per revenue ton.
Can I reduce my W/M charge?
Yes. Reduce packaging volume (tighter packing, removing excess internal packaging), choose FOB terms so you control the freight booking, consolidate multiple SKUs into fewer, larger cartons, and compare LCL rates from multiple forwarders — rates vary significantly by routing and consolidation service.
Are there minimum W/M charges in LCL?
Yes. Most LCL freight forwarders apply a minimum charge — typically 1 W/M or $50–$100, whichever is greater. Very small shipments (under 0.5 CBM) often pay a flat minimum rather than a true per-CBM rate.
How is W/M different from deadweight tonnage?
Deadweight tonnage (DWT) is a measure of a ship's cargo capacity. W/M is a pricing method for individual LCL shipments. They are related in concept (both measure how cargo uses vessel capacity) but operate at completely different scales and are not interchangeable terms.
Find out whether your LCL or FCL option is more cost-effective. Enter your cargo details and get an instant comparison. Calculate your LCL vs FCL cost with our free tool →