The shipping mode affects your price, your delivery promise and how well your goods arrive. Most exporters use both: sea freight for regular volume and air freight for samples, urgent orders and high-value goods.
Sea freight is much cheaper per kilo and suits heavy or bulky cargo and regular orders, but takes several weeks. Air freight takes days rather than weeks and suits urgent, perishable, high-value or light goods, but costs far more. Air freight is charged on chargeable weight, which is the higher of the actual weight and the volumetric weight, commonly calculated at 167 kg per CBM.
Comparing air and sea freight
| Air freight | Sea freight | |
|---|---|---|
| Speed | Days | Several weeks, depending on the route |
| Cost per kg | High | Low |
| Best for | Samples, urgent orders, perishables, high-value goods | Heavy or bulky goods, regular volume |
| Size limits | Aircraft door and weight limits | Very few, including oversized cargo |
| Transport document | Airway bill | Bill of lading |
| Incoterms | FCA, CPT, CIP, DAP, DDP | FOB, CFR, CIF, or the any-mode terms |
How air freight is charged
Airlines charge on chargeable weight: the higher of the actual gross weight and the volumetric weight. For general air cargo, volumetric weight is commonly calculated as length x width x height in cm divided by 6,000, which equals 167 kg per CBM. Express courier services often use a divisor of 5,000, which makes light, bulky parcels more expensive.
For example, a carton of 60 x 50 x 50 cm weighing 12 kg has a volumetric weight of 25 kg at the 6,000 divisor, so you pay for 25 kg. Our free CBM calculator works out volume and weight for your cartons.
When air freight makes sense
- Samples and trial orders, where speed wins the order
- Perishable goods such as fresh produce and flowers
- High-value, low-weight goods such as jewellery, pharmaceuticals and electronics
- Urgent orders, or a late order where missing the buyer's deadline costs more than freight
When sea freight makes sense
- Heavy or bulky goods such as grain, stone, furniture or machinery
- Regular orders where the buyer plans stock well ahead
- Price-sensitive products where freight is a large share of the landed cost
For sea freight, see our guides to FCL vs LCL and container sizes.
Frequently asked questions
How is air freight volumetric weight calculated?
For general air cargo, multiply length, width and height in centimetres and divide by 6,000. Express couriers often divide by 5,000. You pay on the higher of this and the actual weight.
Is sea freight always cheaper?
Per kilo, almost always. For very small, light shipments, the fixed port and handling charges of sea freight can make air or courier competitive.
Which Incoterms should I use for air freight?
Use any-mode terms such as FCA, CPT, CIP or DAP. FOB and CIF are only for sea and inland waterway transport.
Check your shipment size
Use the free CBM calculator to work out volume and weight before you compare air and sea freight quotes.
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