Timber container load: when weight beats volume
Packs of planed softwood in a 40 HC — how many fit by volume, how many the payload allows, and how many containers the shipment really needs.
The job
An exporter books 40 HC containers for planed softwood. Each pack measures 2.40 × 1.15 × 1.10 m and the timber runs about 500 kg/m³ at shipping moisture. The clerk fills the container on paper by volume, divides the order by that number, and books six containers.
Inputs
| Item | Value |
|---|---|
| Container | 40 HC |
| Pack size | 2.40 × 1.15 × 1.10 m (3.036 m³) |
| Timber density at shipping MC | 500 kg/m³ |
| Mass per pack | 1,518 kg |
| Packs to ship | 120 |
How it was calculated
Container loading compares two ceilings on the same cargo: usable volume ÷ volume per pack, and payload ÷ mass per pack. The smaller of the two is the real limit — cube out or weigh out. Internal dimensions and payload come from carrier specifications and stay editable, because payload varies by carrier and route. The stowage factor is shipment volume divided by mass in tonnes, checked against the IMO CSS Code ranges for wood cargo.
What the calculators return
| Item | Value |
|---|---|
| Packs allowed by volume | 22 |
| Packs allowed by payload | 17 |
| Packs per container (binding limit) | 17 |
| Volume / payload utilisation | 75.9% / 97.4% |
| Stowage factor | 2.00 m³/t |
Compared with the usual approach
| Item | Planned on volume only | Volume and weight checked |
|---|---|---|
| Packs per container | 22 | 17 |
| Containers for the order | 6 | 8 |
| Loaded weight per container | 33,396 kg | 25,806 kg |
Every number on this page is recomputed at build time by the calculators themselves — nothing is typed in by hand.
Takeaway
The container cubes out at 22 packs but weighs out at 17: the payload runs out while a quarter of the box is still empty air. Planning on volume alone books six containers for this order instead of the eight it actually needs — a two-container error caught at the quote rather than at the terminal weighbridge, where it costs a re-stuff. The stowage factor of 2.00 m³/t lands inside the IMO range for sawn timber, which is the sanity check that the density assumption was sound in the first place.