Buyer tool · carton arithmetic, estimate only
Packing and Container Loading: How the Arithmetic Works
Easels and canvas fill a container by volume as much as by weight, and the volume is decided by carton design rather than by the product alone. This page explains how the carton cube is calculated from the dimensions on a model page, how a mixed order is estimated, and where the estimate stops being reliable. Nothing here is a guaranteed loading figure: the loading plan is built from the packing list of the batch you order.
Carton cube is length x width x height in metres, per carton. For a mixed order, multiply each model's cube by the number of cartons, add the results, and compare the total with the container's usable volume: a 40-foot high-cube container has roughly 68 m3 of nominal internal volume and about 55-60 m3 of usable space after packing losses. Treat the result as a planning estimate and confirm the load against the batch packing list.
At a glance
| Cube formula | length x width x height (m) per carton |
|---|---|
| 40HQ nominal | roughly 68 m3 internal; about 55-60 m3 usable in practice |
| 20GP nominal | roughly 33 m3 internal; about 28 m3 usable in practice |
| Weight limit | easels usually cube out before they weigh out; bars add weight per carton |
| Data source | carton dimensions recorded per model where the supplier records them |
| Status | estimate for planning only - confirmed against the batch packing list |
Worked example: estimating a mixed order
| Model group | Carton size (cm) | Cube per carton | Cartons | Cube total |
|---|---|---|---|---|
| Children's floor easel | example 60 x 40 x 12 | 0.0288 m3 | 120 | 3.456 m3 |
| Mini display easels | example 45 x 35 x 30 | 0.0473 m3 | 30 | 1.418 m3 |
| Canvas stretcher bars | example 95 x 12 x 12 | 0.0137 m3 | 80 | 1.094 m3 |
| Studio H-frame easel | example 155 x 45 x 20 | 0.1395 m3 | 20 | 2.790 m3 |
| Total | - | - | 250 | 8.758 m3 |
The carton dimensions in this table are worked examples, not catalogue data. The recorded carton dimensions for each model are on its product page where the supplier records them. The total is a planning estimate; palletisation, dunnage and the container's own shape reduce the usable volume.
What changes the arithmetic
| Factor | Effect on the load | What to confirm |
|---|---|---|
| Carton design | a carton 20% bigger is 20% more freight | confirmed carton dimensions per batch |
| Palletisation | pallets consume volume and add height | pallet or floor-loaded? |
| Mixed models | odd carton sizes leave gaps | carton list and loading plan |
| Weight | heavy models hit the limit before the volume | gross weight per carton |
| Dunnage | protection adds cube | packing specification per model |
This page is deliberately an estimate tool, not a fact block. The catalogue does not publish a container quantity per model because that figure depends on the batch, the pallet plan and the forwarder.
How it runs
- Read the carton dimensions and units per carton from each shortlisted model page.
- Convert centimetres to metres and multiply to get the cube per carton.
- Multiply by the number of cartons per model and add the models together.
- Compare the total with the usable volume of the container, not its nominal volume.
- Send the carton list with the order so the loading plan can be built from the batch packing list rather than from an estimate.
Why easels cube out before they weigh out
- An easel is mostly air in the carton: the legs splay, the panel is thin and the frame is light. The result is a product that fills a container long before it approaches the weight limit.
- That is why carton design matters more than product cost on a volume order. A carton that is 20 per cent larger costs 20 per cent more freight per unit, which can be more than the difference in unit cost between two suppliers.
- Canvas bars are the exception on weight per length: a carton of long bars is heavy for its cube, so a mixed order with bars in it should be planned on both volume and weight.
- Stretched canvas is the other extreme: bulky, light and awkward to palletise, which is why the carton count and the cube are published per model rather than described as a container quantity.
Where this estimate stops being reliable
- The catalogue does not publish a guaranteed container quantity per model. The real figure depends on the carton list of the batch, the pallet plan, dunnage and the forwarder's loading.
- Palletisation can cost a fifth of the usable volume, and whether a shipment is palletised is a buyer and forwarder decision rather than a product one.
- A mixed order of odd carton sizes leaves gaps that no cube formula predicts; the loading plan is the only reliable number.
- Weight is checked separately: a 20GP with a heavy bar order can reach its payload limit with room to spare in volume, and that is a different plan from a light easel order.
FAQ
How do I calculate CBM for an easel order?
Take the carton dimensions in centimetres, convert to metres and multiply length x width x height. That is the cube per carton. Multiply by the cartons per model and add the models together for the order total. The carton dimensions are on each model page where the supplier records them. The result is a planning estimate, not a loading guarantee: pallets, dunnage and mixed carton sizes all reduce the usable volume.
How many easels fit in a 40HQ container?
There is no single answer, and a catalogue that quotes one is guessing. It depends on the carton cube per model, the mix, and whether the load is palletised. As a planning reference, a 40-foot high-cube container has roughly 68 m3 of nominal internal volume and about 55-60 m3 usable after packing losses. Divide the usable volume by the carton cube to get a rough carton count, then confirm against the batch packing list before booking freight.
Is the packing data on the product pages confirmed?
Where the supplier records carton dimensions and weight, the page publishes them and they are the values we plan from. Where the record has no carton data, the page says so and the figure is confirmed per batch. The distinction matters: a confirmed carton dimension and a confirmed-on-batch dimension are not the same input to a freight calculation, and we label them differently.
Planning a mixed container?
Send the shortlist and the quantities; we return the carton list and a loading estimate built from the recorded data, then confirm it against the batch packing list.