It depends mainly on the form and the pack. Dense forms such as powder and granules load much more weight into a 20 ft container than large flakes, which are bulky and fill the space long before they reach the weight limit.
As a very rough illustration, flakes may load well under 10 tonnes in a 20 ft, while powder and granules may reach the low to mid teens. Treat these as starting points only, and ask the plant for its last actual loading of the same form and pack.
Why the form makes such a difference
Dehydrated onion is light. The space it takes depends on bulk density, which is how much a given volume weighs. Large flakes trap a lot of air between pieces. As pieces get smaller, they pack more tightly and the same carton holds more weight.
- Large flakes and sliced: lowest bulk density, fewest tonnes per container.
- Kibbled and chopped: somewhat denser than flakes.
- Minced: denser again.
- Granules: much denser.
- Powder: usually the densest form, and the most weight per container.
How packing changes the number
- Carton size and net weight: common cartons hold a set net weight of product in a liner. The carton size decides how many fit across and up the container.
- Bags: some forms ship in bags with liners, which can fit more product but protect it less.
- Pallets: palletised loads are easier to unload but take space and reduce the number of cartons.
- Loose or floor loaded: cartons stacked by hand use space best but take longer to unload.
- Stacking height: fragile cartons cannot be stacked as high, so some space stays empty.
20 ft or 40 ft?
Because flakes and kibbled onion fill space before weight, many buyers of these forms choose a 40 ft container. It gives roughly twice the space for a freight cost that is often well under twice as much. For powder and granules, a 20 ft can be closer to full use.
If you need more weight per box, you can mix denser and lighter forms in one container. Our article on mixing onion and garlic forms explains how.
What to ask the supplier
- Their last actual loading of your form in your pack, in cartons and net kilograms.
- The carton dimensions and net weight per carton.
- Whether they will load on pallets or floor load.
- A loading plan or photo of a recent loaded container.
- The shipping line's weight limit for your route, if your form is dense.
Why this matters for price
Freight is paid per container, not per tonne. A container that loads fewer tonnes carries a higher freight cost per kilogram. When you compare quotes, check that each supplier assumes the same loading. Our general guide to container loads covers other agri products.
How Creston & Co handles this
We confirm the real loading for your form and pack from the plant's records, agree the loading plan, and supervise the stuffing to check carton counts and condition. To plan your first container, ask for a free sourcing review.