Reefer Container

A reefer container is the workhorse of the cold chain — when you ship anything that spoils, melts or degrades at the wrong temperature, this is the box that keeps it within spec from origin to delivery. Unlike a dry box, it is active equipment you have to keep powered the whole way.

How a reefer keeps cargo at temperature

A reefer is not just an insulated box. It carries an integral refrigeration unit at one end that actively heats or cools the air inside, holding a temperature you set on the controller. That unit needs a constant power supply:

• At sea — it plugs into the vessel's reefer sockets.
• At the terminal or depot — it plugs into a quayside or yard plug point.
• On the road — it runs off a diesel generator set (genset) clipped to the container or built into the chassis.

Because it relies on power, a reefer move is monitored more closely than a standard load. Set-point temperature and airflow are logged, which matters for pharma and fresh produce where you need proof of an unbroken cold chain.

Reefer container specifications

Reefers come in the same external footprints as standard boxes, but insulation and the cooling unit eat into the usable space, so internal capacity is smaller than the equivalent dry container.

Spec	20 ft Reefer	40 ft High Cube Reefer
Temperature range	approx. -30C to +30C	approx. -30C to +30C
Internal length	approx. 5.4 m	approx. 11.5 m
Internal capacity	approx. 28 m³	approx. 67 m³
Power	ship / terminal plug or road genset	ship / terminal plug or road genset

The figures are indicative — exact internal volume varies by manufacturer and unit. See container dimensions for the full set of internal measurements and payloads.

What reefer containers are used for

Anything with a temperature window travels in a reefer:

• Fresh produce — fruit, vegetables, salads kept chilled to slow ripening.
• Frozen goods — meat, fish, ready meals held below freezing.
• Dairy and chilled food — products that need a tight chilled band.
• Pharmaceuticals — vaccines and medicines on validated temperature profiles.
• Flowers and plants — cut flowers shipped just above freezing to extend shelf life.

For Baltic shippers this usually means seafood, frozen processed food and pharma moving in and out of the region. When you need a quote for a temperature-controlled load, UMERA turns your reefer requirement into booked carrier quotes through a single freight RFQ, so you compare real prices instead of chasing carriers one by one.

FAQ

What is a reefer container?

A reefer is a refrigerated shipping container with a built-in cooling unit that holds cargo at a set temperature, roughly -30C to +30C, throughout the journey. It needs continuous power from the ship, terminal or a road genset.

What sizes do reefer containers come in?

The two common sizes are the 20 ft reefer and the 40 ft High Cube reefer. Both have a smaller internal capacity than a dry box of the same footprint because of the insulation and refrigeration unit.

Does a reefer container need power on the road?

Yes. On the road it runs off a diesel generator set (genset) attached to the container or chassis, since there is no mains supply on a moving truck. At sea and in the terminal it plugs into reefer sockets instead.

What is the difference between a reefer and a dry container?

A dry container is a passive insulated box with no temperature control, while a reefer actively heats or cools its interior. A reefer also has slightly less usable space and must stay powered, so it costs more to ship.