English
Français
One Carton, Three Divisors: How Air, Courier and Sea Measure It
The same carton can be billed on a 12 kg basis through one channel and on a volume-led basis through another, because air, courier and ocean groupage convert cubic centimetres to kilograms with different divisors. The desk at SBT FulfillDock measures every outbound carton before booking, and this piece reads one carton against all three.
The site's volumetric-weight FAQ covers one mode, as do the parcel weighing and out-of-gauge pages. This is the cross-mode comparison table, not another single-mode explanation.
Key facts, all conventions rather than prices.
- General air cargo: the greater of the two figures on the scale and the cube, at 6,000 cm3 to 1 kg, so 1 m3 reads about 167 kg.
- Courier and express: a 5,000 divisor, common market practice rather than the air standard.
- Ocean LCL: W/M, weight or measurement, whichever is greater, at 1 m3 to 1,000 kg.
- Timing: measured in the China warehouse and carried into the booking; a mismatch opens an exception: 2 hours to a named owner, 24 to a closed ticket.
- Bands: on air DDP we estimate 4-6, 5-9 and 8-12 working days by channel; sea DDP estimates 18-25 calendar days on a west-coast United States sailing and 28-38 days for Europe.
Three conventions, one carton
The conventions disagree on one thing: what a cube is worth to a channel. Air charges whichever reading is higher between the scale and the cube, a groupage sea booking compares weight with measurement, and courier practice sits between. Our example carton, 60 x 40 x 30 cm and 8 kg, is 72,000 cm3 or 0.072 m3.
| Convention | Compared | Ratio used | The example carton |
|---|---|---|---|
| General air cargo | Actual against volumetric | 6,000 cm3 to 1 kg, so 1 m3 is about 167 kg | 12 kg basis against 8 kg actual |
| Courier and express | Actual against volumetric | 5,000 divisor, practice not an air standard | 14.4 kg basis, no repacking |
| Ocean LCL | W/M, weight or measurement | 1 m3 treated as 1,000 kg | 0.072 m3 beats 8 kg: volume-led |
Two rows read it as a weight question, the third as a space question, so bulky low-density freight suits groupage.
A divisor is a channel property, not a price
Divisors belong to channels the way seat pitch belongs to an aircraft: nobody invents one per customer. The 6,000 ratio, the 5,000 courier practice and the 1,000 kg sea tonne state which of two measured figures a channel may use. A carton can be light in one mode and heavy-billed in another, and the measured carton, not the declared one, decides which lane is open; lanes we book are on the DDP sea and air freight service page. We publish no rate card: a quotation is built lane by lane from the packed size, the weight, the cargo type and the destination; nothing here is an offer.
What we measure, and when the number is fixed
The bench decides, before the booking rather than after the invoice. Cartons are weighed and dimensioned in the China warehouse handling the order: B2C parcels through Dongguan, palletised freight through Shenzhen, Yangtze-delta volume through Suzhou, three sites covering 24,000 m2. Those figures form one record, and the volumetric result uses the booked channel's divisor.
That record travels with the booking, so the carrier receives the measurement we hold. A disagreeing re-measure by the channel is an exception, not a footnote: an owner is named within 2 hours and the ticket closes within 24. No minimum order quantity applies, every node is tracked and the desk corresponds in English; a confirmed lane is booked through our contact page.
How density pushes a carton off a transit band
A band describes a channel matched to the measured carton, so density moves shipments between bands. Each window is estimated rather than promised.
| Band | Window | What decides it |
|---|---|---|
| Air DDP, express | 4-6 working days, estimated | Cartons near their scale weight |
| Air DDP, standard | 5-9 working days, estimated | Light cartons reading heavier on volume |
| Air DDP, economy | 8-12 working days, estimated | Denser freight trading speed for steadiness |
| Sea DDP, US West Coast | 18-25 days, estimated | Bulky volume better handled on W/M |
| Sea DDP, Europe | 28-38 days, estimated | Bulk where density beats the calendar |
A low-density carton is pushed off the bands its weight alone would qualify for. Carrier schedules, seasonal capacity and customs handling move them; these bands describe the channel we book, not a delivery guarantee.
The customs figures are separate from the billing figures
Chargeable weight answers to the channel; declared value, the commodity code and an accurate goods description answer to customs; the two are not interchangeable. A declared value is the number the transaction supports, not a lane-selection tool: padding it to clear a threshold, or trimming it below a duty ceiling, is not a lever we will pull and not papers we will file. Compensation is measured against the value declared when the booking was made, so an invented figure costs twice - see our liability and compensation page.
The European Union changed the duty treatment of a low-value shipment from 1 July 2026, with a transition running to 1 July 2028; dates and structure appear here, no amount. The data requirement is unchanged: a code and description matching the carton, filed by us acting as the authorised agent of the shipper.
Where this comparison does not apply
Divisors differ by channel, tier and contract, and they can change, so confirm the ratio in force on the booked lane. The maths never overrides a ceiling: a carton failing a channel's size or weight limit goes to another lane whatever the divisor says. Cargo type sits outside it too: cells and batteries and regulated goods are confirmed channel by channel. This is a comparison of conventions, not a quotation.
Frequently asked questions
Which volumetric divisor applies to my carton, 6,000 or 5,000?
The divisor is whichever one belongs to the channel your carton books on, so neither figure is universal. Air cargo converts at 6,000 cm3 to 1 kg, while 5,000 is common courier practice rather than the air standard. Ocean groupage uses neither: a W/M basis reads 1 m3 as 1,000 kg. Confirm the ratio in force on the lane before repacking to chase a divisor, because the measured carton, not the arithmetic, decides which channel is open to it.
Does a bulky but light carton always qualify for an air band?
A bulky carton does not qualify on scale weight alone, because the channel sees the volumetric figure. At 6,000 cm3 to 1 kg an 8 kg carton can present as a 12 kg basis. The air bands sit at estimated 4-6, 5-9 and 8-12 working days only once a measured carton fits. Size and weight ceilings are tested before any band, so freight outside a channel's limits moves to a different lane rather than into a slower window.
Do you measure cartons before booking or trust my packing list?
We measure cartons before booking and treat a packing list as a claim until the bench agrees. Each carton is weighed and dimensioned in the China warehouse, and that record travels with the booking. A channel's disagreeing re-measure opens an exception, with an owner named within 2 hours and the ticket closed within 24. The list is then reconciled against the bench figure we hold, not against the number that was declared to us.
Reviewed 2026-10-28 (28 October 2026). The three-city floor, the 2 and 24 hour exception clocks and the transit bands are this site's own figures on that date. The divisors are not ours: 6,000 cm3 to 1 kg, the 5,000 courier practice and the 1,000 kg sea tonne are market conventions we book against, not ratios we set and not figures read at source.
Shenzhen Shibotong International Logistics Co., Ltd., the company behind SBT FulfillDock.
