How each mode is billed
Sea LCL (less than container load) is billed per cubic metre, with a minimum of about 0.5–1 m³. Weight barely matters until the cargo is very dense. Air freight is billed per kilogram, on the greater of actual weight and volumetric weight, where volumetric weight is L × W × H in centimetres divided by 6,000. Express couriers use a divisor of 5,000, which makes light, bulky goods even more expensive.
So the deciding variable is density: kilograms per cubic metre. Air punishes bulk, sea does not care about weight.
The density rule
| Cargo density | Example products | Air billed weight | Verdict |
|---|---|---|---|
| Under 100 kg/m³ | Pillows, plastic organisers, foam products | Volumetric, far above actual | Sea, almost always |
| 100–167 kg/m³ | Apparel, small appliances, toys | Volumetric, slightly above actual | Sea for restocks, air for launches |
| 167–300 kg/m³ | Electronics, cosmetics, hardware | Actual weight (at 167 kg/m³ the two are equal) | Air is competitive on high-value goods |
| Over 300 kg/m³ | Metal parts, tiles, batteries (sea only for lithium) | Actual weight | Sea on cost; air only for urgency |
Worked example: 3.2 m³, 640 kg
A restock of 3,200 kitchen organisers in 48 cartons: 3.2 m³, 640 kg, density 200 kg/m³, from Dongguan to a Los Angeles 3PL.
| Sea LCL, DDP | Air freight, DDP | |
|---|---|---|
| Freight | 3.2 m³ × $190 = $608 | Volumetric 3.2 × 1,000,000 ÷ 6,000 = 533 kg; actual 640 kg; billed 640 × $5.2 = $3,328 |
| Origin handling, repack | $156 | $156 |
| Destination handling, delivery | $240 | $190 (airport to door) |
| Customs, duties | $697 | $697 |
| Insurance | $72 | $72 |
| Total | $1,773 | $4,443 |
| Per unit | $0.55 | $1.39 |
| Door to door | ~34 days | ~9 days |
Sea saves $0.84 per unit, $2,670 on the shipment. Air saves 25 days. Whether 25 days is worth $2,670 depends on what being out of stock costs you.
The cost of waiting
If this product sells 100 units a day at $6 margin, a stock-out costs $600 a day in lost margin plus the ranking damage on Amazon that takes weeks to recover. Four days of stock-out erase the freight saving. In that situation air is the cheaper mode.
The fix is not to pay for air every time; it is to order early enough that sea arrives before you run out. Sellers who run 45 days of cover ship by sea; sellers who run 10 days of cover pay for air and call it a freight cost when it is a planning cost.
A simple rule
- Launches and first orders: air for the first 10–20% of units so you can start selling, sea for the rest.
- Steady restocks: sea LCL, ordered with 45–60 days of cover.
- High-value, dense goods (over $30 per unit, over 167 kg/m³): quote both; air is often within 10% on landed cost.
- Anything under 100 kg: courier, because the fixed costs of sea LCL exceed the saving.
- Lithium batteries: sea or dedicated dangerous-goods air; standard air freight will not accept them.
Frequently asked
What is the minimum shipment for sea LCL from China? +
Around 0.5 m³ or 100 kg. Below that the fixed origin and destination charges make courier cheaper despite the higher per-kg rate.
How is air freight volumetric weight calculated? +
Length × width × height in centimetres divided by 6,000 gives kilograms. A 60 × 40 × 40 cm carton is 16 kg volumetric regardless of what it weighs. Express couriers divide by 5,000.
Can the same shipment be split between sea and air? +
Yes, and it is the standard approach for launches: a few cartons by air to start selling, the balance by sea to arrive before the air stock runs out.
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Figures are indicative floor rates and typical fee ranges on our lanes as of Oct 11, 2026. Duty rates depend on your product's tariff code and declared value. This is general information, not customs or legal advice.