Français
Español
Sea-Air Freight Pricing: Two Weight Systems, One Invoice
What the Combination Actually Is
Sea–air freight is one shipment that uses two carriage contracts. Containers leave a factory or a consolidation warehouse, travel by sea to a transfer hub, are unloaded and re-booked onto an inbound air build-up, and fly the remaining distance to a destination airport where a clearance and delivery leg finishes the job. The buyer sees one tracking story. The operator sees two weight systems, two sets of cut-offs, two owners of the cargo at different moments, and a hub where the handover can quietly add days.
That structure produces the honest sales pitch for the mode and the honest limit of it at the same time. The combination is cheaper than moving everything by air because part of the distance is covered at ocean economics. It is faster than everything by sea because the long, slow portion is cut short while the goods are still inland. It is not a discounted air ticket, and a quotation that presents it that way usually hides the part that decides the price.
Two Ratio Systems on One Invoice
Air and ocean do not measure the same carton the same way, and the difference is not small.
- The air side charges the greater of actual gross weight and volumetric weight, with the industry’s customary conversion of one cubic centimetre of volume to one kilogram divided by 6,000 — which works out to roughly 167 kilograms charged for every cubic metre of space the cargo occupies.
- The ocean side, for less-than-container cargo, charges in revenue tons: one cubic metre or one metric ton, whichever is worth more, a ratio of 1:1,000.
Put those two numbers side by side and the whole mode explains itself. A cubic metre of cartons that weigh less than 167 kilograms is still charged as 167 kilograms on the flown portion, so the goods pay for space rather than substance. On the water the same cubic metre is one revenue ton and the light weight buys nothing back either. Both legs bill air; only the air leg does it at a unit price that makes the difference visible on the invoice. That is why a dense, valuable carton survives being partly flown, while a bulky, light one can make the hybrid cost more than the buyer expected once the flight portion is measured against the actual weight.
Worked Example: One Shipment, Three Answers
Take a hypothetical ten-pallet consolidation: 18 cubic metres, actual gross weight 1,150 kilograms, soft goods in cartons. Nothing here is a price; the point is which number each leg would bill.
| How the cargo moves | What the billing measurement becomes | What it shows |
|---|---|---|
| All ocean, groupage | 18 revenue tons (volume beats weight at 1:1,000) | The slowest option bills on space, and the goods’ light weight buys nothing back. |
| All air | 3,000 chargeable kilograms (18 m³ at roughly 167 kg per m³) | Nearly three times the real weight on the scale. |
| Sea–air split 14 m³ sea, 4 m³ air | 14 revenue tons plus about 668 chargeable kilograms | The air exposure is cut by roughly four fifths; the speed is cut by far less than that. |
Now change one input: same cube, but machinery parts at 4,600 kilograms actual. All-air would now charge on real weight rather than volume, because 4,600 exceeds the volumetric figure. The hybrid’s saving shrinks. Density, not urgency, decides how much the air portion costs — and density is the number most sellers never put in front of a forwarder.
The Air Leg Sets the Floor
Because the flown portion is measured by the stricter ratio and priced in a market that clears on capacity rather than on inventory, it dominates the total. Two practical consequences follow.
- Compressing and repacking is worth more on a hybrid lane than on an ocean lane. The same centimetres removed from a carton are worth about ten times as much when the goods are billed on the air ratio for part of the trip.
- A hub that can only feed one airline is a pricing problem, not an operational one. Air capacity at a transfer point is sold by the weight bracket; a lane with a single carrier offers no alternative build-up when a flight is full, and the quote you accepted assumed a space that somebody else controls.
What the sea leg contributes is not just cheapness. It contributes the part of the journey where a delay costs least — which is why the sensible place to put the boundary between the two modes is the longest stretch of open water, not the earliest hub on the map.
Where the Break-Even Moves
Ask a forwarder “when does sea–air win?” and the truthful answer has three variables rather than one date.
| Variable | Favours the hybrid | Favours pure air or pure ocean |
|---|---|---|
| Density | Light goods in real volume, where air’s 1:6,000 ratio punishes a full-air move | Dense cargo (all air stops being punished on volume) or very heavy, low-value cargo (all ocean) |
| Distance left to cover after the hub | A short sea leg and a long air leg — a hub that is close to the origin, far from the destination | A hub that leaves the flight no distance to save |
| Value of the goods | Fast-moving stock where every extra week on water ties up working capital and risks a stock-out | Slow-moving, low-margin inventory where the carrying cost is smaller than the freight gap |
The second row is where most bad routing decisions are made. A hub chosen for its reputation rather than its position relative to the destination airport produces a lane in which the goods spend weeks crossing water, then days waiting for an air connection that saves less time than the wait costs.
Hub Dwell Is the Line Item With No Owner
In a single-contract ocean move, the cargo is either loaded or it is not. In a hybrid move there is a period between discharge on one side of the hub and uplift on the other that belongs to neither carrier. It usually contains: de-consolidation, a second security screening before the goods can enter an air build-up, temporary storage, and a handover document that has to be re-issued in a different format for the air leg.
Two things to ask, in writing, before booking: who is accountable for those days, and what happens to the rate if the dwell runs past the window the quote assumed. A lane that promises a door-to-door range without naming the hub’s own clock is quoting the sum of two schedules that were never reconciled.
Six Numbers to Demand Before You Accept a Hybrid Quote
- Your cargo’s actual weight and its total volume, both measured after packing — not the factory’s estimate.
- The chargeable figure the air portion will bill, and the ratio used to get it.
- The revenue-ton figure the ocean portion will bill.
- The named hub, and the days between vessel discharge and uplift that the plan allows.
- Which carrier or agent owns each leg, and whether the air portion is confirmed space or best effort.
- The transit range stated as approximate, with what it is counted from — vessel departure, hub arrival or collection date.
We consolidate in three connected domestic warehouses totalling 24,000 square metres, re-measure cartons before quoting a hybrid split, and put the ratio and the hub window into the price line rather than leaving them to surface on invoice. Every day count we give is an estimate; what moves it is the vessel rotation, the dwell at the transfer point and the season. Send the volume, the actual weight and the destination, and you get the sea portion, the air portion and the handover as three separate lines — including the answer when the arithmetic says a hybrid is the wrong mode for your goods.
