How the airline actually bills you

Air freight is charged on chargeable weight — the higher of actual (gross) weight and volumetric weight. Volumetric weight converts the space your shipment occupies into kilos using the standard air divisor of 6,000:

volumetric kg = (length cm × width cm × height cm) ÷ 6,000

A 60 × 40 × 50 cm carton weighing 12 kg has a volumetric weight of 20 kg — and you pay for 20. This is why the single cheapest air-freight decision is usually made in the packing area, not in the negotiation: tighter cartons and less void fill lower the bill directly.

The comparison people get wrong

Comparing air and sea on freight rate alone always favours sea. The honest comparison includes what the extra transit time costs you:

• Capital tied up in transit. Goods on the water are cash you cannot use. Multiply the shipment value by your cost of money for the extra weeks.
• Safety stock. A long, variable lead time forces you to hold more inventory to cover it — permanently.
• The cost of being late. A stock-out, a stalled production line, a contract penalty or a missed season is rarely smaller than the freight difference.
• Insurance and risk exposure over a longer, multi-handling journey.

When air is the right call

• High value, low volume — electronics, instruments, pharmaceuticals, precision spares.
• Production-critical spares where downtime is billed by the hour.
• Perishables and shelf-life goods, where sea transit consumes the sellable window.
• Launches, tenders and seasonal deadlines with a fixed date.
• The first shipment of a new product, so the market test is not delayed by six weeks.

The split most importers miss

It is not either/or. Send the fast-moving or urgent portion by air and the bulk by sea on the same purchase order: the line keeps running while the volume travels cheaply. For a regular flow, that split is usually cheaper than committing everything to one mode.

What still has to be right

Air freight compresses transit, not compliance. The ACI registration, the classification, the permits and the document set are the same — and with only hours of transit, a document problem is discovered at the airport rather than three weeks before arrival. Air shipments need their paperwork finished earlier in relative terms, not later.

Get the real comparison

Ranisy quotes air and sea side by side on your actual dimensions and timeline — chargeable weight calculated from your packing list, landed cost including duty, VAT, handling and delivery. Send us the carton dimensions and the date you need the goods and we will show you which mode is genuinely cheaper for that shipment.