Twenty kilograms of tomatoes is a volume question and a handling question, and the volume question is the smaller one. Tomatoes are roughly as dense as water, so twenty kilograms occupies a bit over twenty litres of solid volume – and a crate holds considerably more than that because fruit does not pack solid. A crate of around thirty-five to forty-five litres nominal capacity will take twenty kilograms of round tomatoes comfortably without heaping.
That number is close to useless on its own. What actually decides the crate is the next three things.
Field heat and vent area
Tomatoes picked warm carry field heat that has to leave before they go into a cold chain, and it leaves through the crate walls. Vent area as a share of the wall surface is the number that matters, and it is usually expressed as a percentage. More is better for cooling and worse for bruising, because fruit sags into openings.
A crate that is excellent for cucumbers can be wrong for vine tomatoes purely on vent geometry. Tell your supplier the crop, not just the weight.
Stack height and truck cubes
Crates are bought to fit a vehicle. A crate that is fifty millimetres too tall means you lose a layer in the truck, and that is a cost you pay on every load for the life of the crate. Before settling on a size, check the crate against the actual internal height of the vehicle or the container, and against the pallet pattern you run.
The common mistake is sizing for capacity and discovering later that the crates stack to a height that wastes seventy millimetres of headroom. Get the stack height first and work backwards to the crate.
Picked into, or packed into?
A crate used in the field has to be carried, often one-handed, often up a ladder or along a row. That limits weight and it matters for handle design. A crate used on a packing line never gets carried by a picker and can be optimised for volume and ventilation instead.
These are different products. If you ask for “a 20 kg tomato crate” without saying which, you will get a compromise that is mediocre at both.
And the honest part about fill weight
Twenty kilograms is a nominal figure and real fills drift upward, particularly at the end of a day when everyone is hurrying. A crate specified exactly at twenty will spend its life at twenty-three. Size for what the fill actually reaches, not what the label says – and if you want to know how the crate holds up after a few seasons of that, we covered how many trips a PP crate survives.
What the crate has to survive
Sizing for the crop is half the job; the other half is the season. A crate that will be filled and stacked two hundred times, hosed down, and left in a yard between runs needs a different wall section and a stabilised resin from one that goes from packing house to supermarket and back in a week.
Worth telling your supplier the wash method too. A crate going through a hot tunnel cycle needs to be specified for the temperature, and that is a resin and wall question rather than a size question. We covered it in can PP crates go through an industrial wash tunnel.
What we can do
We make PP crates for fruit and vegetables and we will ask about the crop, the fill, the stack height and who carries it before quoting anything. Give us those four and we will specify a crate – or tell you one of our standard sizes already fits, which is often the case and always cheaper.