Reefer Container Dimensions & How to Load Refrigerated Cargo

Quick answer: A 40ft reefer (refrigerated container) has an internal volume of about 59 m³ and a payload of roughly 29,000 kg — meaningfully less room than a dry 40ft (~67 m³), because the insulated walls and the built-in cooling unit take up space. A 20ft reefer holds about 28 m³. And unlike a dry box, you can’t load a reefer to the roof or wall-to-wall: the cold air has to circulate, so the red load line and the T-floor set hard rules for how cargo is stacked.

If you plan a reefer load like a dry container, you’ll either over-book on volume that isn’t there or block the airflow that keeps the cargo in spec. Here’s how to get both right.

Plan to the real reefer interior, not the dry-box number. Pick a reefer preset and enter your cargo to see how it fits the smaller insulated interior, how full it runs, and where the weight sits — free, no signup.

Check my reefer load free →

Reefer vs dry container: why the interior shrinks

A reefer is a dry container’s dimensions on the outside, but the insulation (typically 60–100 mm of foam in the walls, floor and ceiling) and the integral refrigeration unit at the front end both eat into the usable space. The result: a reefer of a given length is always tighter inside than the dry container it looks like from the outside.

	20ft reefer	40ft High Cube reefer
Internal length	~5.44 m	~11.56 m
Internal width	~2.29 m	~2.29 m
Internal height	~2.27 m	~2.50 m
Volume capacity	~28 m³	~59 m³
Max payload	~27,700 kg	~29,000 kg

Compare that with a dry 40ft’s ~67 m³ and you’re giving up roughly 8 m³ to insulation and the cooling unit. Most reefers ship as High Cube to claw some of that height back — a standard-height 40ft reefer is rarer and tighter still. For every container type side by side, see the shipping container dimensions guide.

The T-floor and the red load line: reefer loading rules

Refrigerated cargo stays in spec only if chilled air can move through and around it. Two features of the container enforce that:

• The T-bar (T-section) floor. The corrugated aluminium floor is designed so cold air pushed up from the front unit travels the length of the container under the cargo and returns over the top. Cargo must sit on this floor (or on pallets/dunnage) so the channels stay clear — you can’t lay a solid sheet across it and block the flow.
• The red load line. A painted line near the ceiling marks the maximum stacking height. Load above it and you choke the return-air path along the roof, so the boxes at the back of the container never reach temperature. The line is a hard limit, not a suggestion.

The practical upshot: a reefer is often height-limited by the load line, not by the roof, and airflow-limited, not just volume-limited. Chilled produce usually needs gaps around the stow for air to circulate; frozen cargo is typically block-stowed tight but still kept under the load line.

How much cargo actually fits

Because of the load line and airflow gaps, a reefer’s usable capacity is lower than even its reduced internal volume suggests. As a rule of thumb:

• Pallets: a 40ft HC reefer takes about 21 Euro or 20 standard pallets on the floor — similar to a dry 40ft, since the floor length is comparable — but double-stacking is constrained by the load line.
• Chilled produce: plan for airflow gaps; effective fill is often 70–85% of the raw volume.
• Frozen, block-stowed: can approach the load-line height wall-to-wall, so fill is higher.

The reefer’s payload (~29,000 kg) is generous, so most refrigerated loads are volume- or airflow-limited, not weight-limited — the opposite of dense dry cargo like tiles or canned goods.

Set-point, fresh-air, and the paperwork that rides along

Loading a reefer isn’t just geometry — the cargo has a set-point temperature, and perishables also need a fresh-air exchange (ventilation) setting to vent the CO₂ and ethylene that produce gives off. Those don’t change how many boxes fit, but they’re part of the same plan, and a mismatch between the set-point your cargo needs and what the container is running is exactly the kind of thing that ruins a shipment on arrival. A load plan that carries a reefer temperature range per item, and flags when a load mixes cargo with incompatible set-points, keeps that visible before the doors close.

Plan the reefer, not a generic box

Refrigerated loads have their own dimensions, their own height limit, and their own airflow rules — planning them like a dry container is how cargo arrives warm or short-shipped. ContainerMath is container loading software with built-in reefer presets that carry the correct reduced interior and payload, so your plan reflects the space you actually have. Tag items with a reefer temperature range and the plan flags an incompatible set-point mix as an advisory; the 3D view shows exactly how the stow sits under the load line before anything is loaded.

Plan a reefer load in 3D — free trial →

Frequently asked questions

What are the internal dimensions of a 40ft reefer container?

About 11.56 m long × 2.29 m wide × 2.50 m high for a 40ft High Cube reefer, giving roughly 59 m³ of internal volume and a payload near 29,000 kg — less room than a dry 40ft because of the insulation and cooling unit.

Why does a reefer hold less than a dry container of the same size?

The insulated walls, floor and ceiling plus the integral refrigeration unit take up space. A 40ft reefer offers around 59 m³ versus roughly 67 m³ in a dry 40ft — about 8 m³ lost to keeping the cargo cold.

What is the red load line in a reefer container?

A painted line near the ceiling marking the maximum stacking height. Loading above it blocks the return-air path along the roof, so cargo at the back never reaches temperature. Treat it as a hard height limit.

Can you load a reefer container to the roof like a dry box?

No. Cargo must stay under the red load line, and the T-bar floor and airflow gaps have to be kept clear so chilled air can circulate. A reefer is usually airflow- and load-line-limited rather than filled to the roof.

How many pallets fit in a 40ft reefer container?

About 20 standard or 21 Euro pallets on the floor — similar to a dry 40ft since the floor length is comparable — though the red load line limits how much you can safely double-stack.