Reefer Container

A reefer container is a refrigerated intermodal shipping container used to move temperature-sensitive cargo such as fruit, vegetables, meat, seafood, dairy, pharmaceuticals, flowers, and some chemicals. Its insulated box and integrated refrigeration machinery are designed to hold a set environment throughout a long multimodal journey.

Unlike a dry container, a reefer is part box and part machine. You are not just booking space. You are booking temperature control, airflow, power access, monitoring, and tighter operating discipline at every handoff from origin packhouse to terminal, vessel, rail ramp, and final delivery.

That is why reefer execution sits at the intersection of container stuffing, yard planning inside the container yard, and inland handoffs such as drayage. If one part of the chain breaks, cargo quality and claims exposure can change fast.

Reefer Container Definition

In practical terms, a reefer container is a standard ISO shipping container fitted with insulated walls, a refrigeration unit, temperature sensors, and forced-air circulation. The unit can cool, heat, dehumidify, ventilate, and record operating conditions depending on the commodity program and the equipment model.

A dry container mainly protects cargo from weather and theft. A reefer container protects cargo from time, heat, freezing, condensation, poor airflow, and temperature drift. That difference matters because many reefer commodities continue to respire or degrade even when they look stable at loading.

• Common reefer cargo includes fresh produce, frozen food, seafood, meat, dairy, flowers, biologics, and temperature-sensitive industrial goods.
• Reefers can run chilled programs for fresh cargo and deep-frozen programs for cargo that must remain below freezing.
• Many modern reefers also support controlled atmosphere, fresh-air ventilation, humidity management, and trip data logging.

Reefer Container Sizes and Specifications

Reefer boxes come in fewer configurations than dry equipment because the refrigeration machinery, insulation thickness, and power design consume space and add weight. The most common operating sizes are 20-foot reefer and 40-foot high-cube reefer, while 45-foot reefer equipment is available in some fleets and trades but is less universal.

Container type	Typical inside dimensions (L x W x H)	Typical capacity	Typical tare	Notes
20-foot reefer	5.45 x 2.28 x 2.16 m	About 28 to 29 m3	About 2.9 to 3.1 t	Dense cargo, lower cube, good for heavy frozen programs
40-foot high-cube reefer	11.58 x 2.29 x 2.55 m	About 67 m3	About 4.6 to 4.9 t	Most common long-haul reefer format today
45-foot high-cube reefer	Varies by carrier and maker	About 80 to 86 m3	About 6.0 to 6.5 t	Less common, often pallet-wide, confirm exact release spec

20-Foot Reefer Container

A 20-foot reefer is often chosen when the cargo is heavy relative to its cube, such as frozen protein or dense packaged food. Typical internal dimensions are roughly 5.45 meters long, 2.28 meters wide, and 2.16 meters high, which produces just over 28 cubic meters of usable space on many fleets.

Because the machinery sits at one end and insulation reduces usable volume, the inside cube is materially smaller than a comparable dry 20. That tradeoff is normal in reefer equipment: you gain climate control but lose some payload and internal volume.

40-Foot Reefer Container

In many shipping lines, the practical 40-foot reefer is a 40-foot high-cube reefer. The extra internal height is valuable for palletized produce, pharmaceuticals, and higher-cube loads. Typical inside dimensions are around 11.58 meters long, 2.29 meters wide, and 2.55 meters high, with about 67 cubic meters of capacity.

This is the size most shippers picture when they discuss reefer shipping programs because it balances useful cube, standardized vessel slots, and broad global availability.

45-Foot Reefer Container

A 45-foot reefer gives more floor area and often better pallet efficiency, but it is not offered in every lane, terminal, or carrier network. Specs vary more than 20-foot and 40-foot equipment, so the right operating assumption is to treat 45-foot reefer dimensions as equipment-specific rather than universal.

If your load plan depends on a 45-foot reefer, confirm not just the nominal size but also pallet-wide capability, maximum gross weight, available plug support, and any destination constraints before booking.

Interior vs Exterior Dimensions

Reefer containers have the same broad external footprint as other ISO boxes so they can move through terminals, on chassis, and on vessels. The interior is different. Insulated sidewalls, an evaporator section, an air-delivery plenum, and the T-floor all reduce usable width, length, and height versus a dry container.

That is why reefer load planning should always use the exact internal dimensions and door opening of the released equipment, not the exterior box size. A pallet pattern that works in dry equipment can fail in reefer equipment once airflow clearances are added.

Reefer Container Temperature Range and Settings

Temperature Range

As a working rule, modern marine reefers commonly operate in a band of roughly -35 C to +35 C, although the exact usable range depends on the unit model, ambient conditions, and the cargo program. Frozen cargo typically runs far below zero, while fresh cargo may move just above freezing or at a mild positive setpoint.

Commodity program	Typical setpoint	Why it matters
Frozen meat or seafood	-18 C or below	Prevents thawing, quality loss, and food-safety risk
Bananas and tropical fruit	About +13 C to +14 C	Avoids chilling injury while slowing ripening
Chilled produce and dairy	About 0 C to +5 C	Balances shelf life with damage prevention
Pharmaceutical cold chain	Often +2 C to +8 C	Protects labeled stability ranges and compliance needs
Chocolate or confectionery	Often +15 C to +18 C	Prevents bloom, deformation, and melt events

Fresh vs Frozen Cargo Settings

Fresh cargo and frozen cargo are managed differently. Frozen cargo usually focuses on maintaining a stable low setpoint. Fresh cargo often requires tighter coordination between temperature, ventilation, humidity, and air circulation because the product may still be alive, respiring, or highly sensitive to dehydration and ethylene.

That distinction is why a reefer booking instruction should never stop at just one number. The commodity, pack style, pulp temperature at loading, and whether the program is fresh or frozen all influence the correct machine setup.

Controlled Atmosphere (CA) and Modified Atmosphere (MA)

Some reefer programs go beyond temperature and manage oxygen and carbon-dioxide levels to slow ripening or biological activity. Controlled atmosphere systems actively manage gas composition over the voyage. Modified atmosphere programs rely more on packaging or a cargo-specific atmosphere strategy established before or during transport.

CA and MA are especially relevant for premium produce and other sensitive exports where transit time is long and the commercial value of shelf-life extension is high. They also add planning complexity, because atmosphere settings, seals, and monitoring need to remain consistent across the trip.

Ventilation and Humidity Controls

Ventilation settings manage the exchange of fresh air and the removal of gases produced by cargo. Humidity settings help protect products that lose value when they dehydrate, sweat, or suffer condensation damage. These settings are not cosmetic. For many fresh commodities they are part of the commodity protocol.

A produce shipper that gets the setpoint right but the ventilation wrong can still deliver damaged cargo. That is why reefer instructions often include temperature, vent setting, drain guidance, and load pattern together rather than as separate decisions.

Temperature Recording and Data Loggers

Most reefer programs rely on continuous machine data, event logs, and in some cases independent data loggers placed with the cargo. These records help prove what the container was instructed to do, whether alarms occurred, and how the environment changed during handoffs or power interruptions.

For claims handling, the difference between a shipper logger, a reefer controller history, and milestone visibility can be significant. One shows cargo-area conditions, another shows machine behavior, and the third shows where in the chain the problem likely started.

How Reefer Containers Work

Refrigeration Unit Mechanics

A reefer unit pulls return air from the cargo space, conditions it through the refrigeration system, and pushes supply air back through the floor and up through the load. Sensors compare return air, supply air, and setpoint conditions so the controller can cycle cooling, heating, defrost, and fan behavior.

The important operational point is that a reefer is designed to maintain product temperature, not rapidly pull field heat out of badly prepared cargo. If warm cargo is loaded, the machine may run constantly while product temperatures remain uneven.

Power Supply

A reefer container needs power almost everywhere except the short moments when it is being transferred between power sources. At origin and destination, it may run from terminal or depot plug points. On the vessel, it runs from dedicated reefer sockets. During inland moves, it may depend on a clip-on or undermount genset mounted for truck or rail transfer.

That power chain is one reason reefer planning cannot be isolated from the inland move. If the drayage plan, rail handoff, or yard slot is not aligned with reefer power availability, temperature risk increases immediately.

Airflow Design

Reefers deliver conditioned air from the machinery end, through the T-floor, and up around the cargo before return air cycles back to the unit. That is why airflow clearance matters so much. Cargo should not crush the floor channels, block return-air space, or be packed hard against the ceiling and doors if the commodity program requires circulation.

Poor airflow is one of the most common avoidable reefer failures. A perfectly healthy machine cannot protect product if the load pattern prevents conditioned air from moving through the cargo space.

Pre-Cooling vs Non-Pre-Cooling

Reefer operators often speak about pre-cooling, but the critical distinction is what exactly is being cooled. The container may be brought to the intended operating condition before loading, but most commodity programs still expect the cargo itself to arrive at or near shipping temperature. The reefer should maintain temperature, not do primary product cooling.

There are exceptions based on commodity and shipper protocol, but as a default rule, loading warm cargo into a reefer and hoping the box will fix it is a poor cold-chain strategy.

Reefer Container Operations

Pre-Trip Inspection (PTI) - What It Covers

PTI is the pre-trip inspection performed before the container is released for cargo. It is meant to catch obvious equipment, sensor, alarm, and control issues before the shipment is at risk on the water. A passed PTI does not guarantee a perfect voyage, but skipping or rushing PTI is a preventable way to invite claims.

• Controller status, alarms, and sensor accuracy checks
• Cooling, heating, fan, and defrost performance
• Door gasket condition, drainage, and structural cleanliness
• Setpoint entry, ventilation settings, and data-logging readiness

Cargo Stuffing Best Practices for Reefers

Good reefer loading starts with the same discipline required in container stuffing, but the tolerance for mistakes is lower because airflow matters as much as cube. Cargo should be precooled where required, packed to allow air movement, and loaded so return-air and floor channels remain open.

• Use commodity-specific loading patterns instead of generic dry-container stacking logic.
• Do not block the evaporator discharge, T-floor channels, or return-air path.
• Verify pulp temperature, packaging ventilation, and pallet condition before loading.
• Seal instructions, vent settings, and booking details should match the commodity program exactly.

Reefer Plugging at Terminals and Container Yards

Once a reefer is handed to the port, depot, or container yard, the plugging process becomes operationally critical. The unit needs to be connected to an available power point, checked into the correct monitoring workflow, and kept in a yard location where plug status can be maintained through dwell time.

Terminals and depots usually have dedicated reefer blocks, but plug capacity is finite. That means early arrivals, missed cutoffs, or unplanned dwell can create real operational pressure, especially in peak perishables seasons. Import teams should also remember that unplanned demurrage exposure is worse on reefer cargo because every extra day may also involve power-related risk.

Monitoring During Transit

Monitoring is not just a nice-to-have for premium cargo. It is how operators catch missed vessel connections, unplugged inland moves, alarm events, and late destination availability before they become spoilage claims. The longer and more fragmented the route, the more valuable milestone visibility becomes.

Track reefer containers in real time with Terminal49 using the Container Tracking API to surface milestones, handoffs, and exceptions that matter for temperature-sensitive shipments.

Reefer Container Costs

Reefer vs Dry Container Rate Premium

Reefer freight usually costs materially more than dry freight because the shipper is paying for specialized equipment, tighter space allocation, more expensive repositioning, power infrastructure, and a higher-service operating model. The premium widens further in seasonal produce trades or when equipment is tight.

Power and Fuel Surcharges

Power is part of the cold chain cost stack. Ocean carriers, depots, terminals, truckers, and rail providers may all recover reefer power or fuel costs differently. The exact line items vary, but importers should expect reefer pricing to reflect electricity, genset fuel, and monitoring effort somewhere in the move.

PTI Costs

PTI may appear as a separate charge or be embedded in an equipment or handling package. Either way, it is not a place to cut corners. The cost of a proper PTI is usually minor compared with the cost of a rejected load or a disputed cold-chain claim.

Genset Rental

When a reefer needs power on the road or rail, genset rental and fuel can become separate budget items. These charges matter most on longer inland legs, at congested gateways, or when the move includes multiple handoffs before the container reaches a stable plug point.

Common Reefer Container Commodities

Reefers are used anywhere product quality depends on environmental control, but some cargo groups dominate global usage because the commercial value of shelf life, temperature stability, and transit integrity is so high.

• Fresh fruits and vegetables such as bananas, berries, grapes, citrus, avocados, onions, and leafy produce
• Meat, poultry, seafood, and frozen prepared foods
• Dairy products, beverages, and confectionery
• Pharmaceuticals, clinical materials, and healthcare products with validated temperature ranges
• Flowers, seeds, plant materials, and selected chemicals or resins that need controlled transport

Reefer Container FAQs

What is a reefer container?

It is an insulated intermodal shipping container with an integrated refrigeration unit that maintains a specified environment for temperature-sensitive cargo during port, ocean, rail, and truck moves.

What sizes do reefer containers come in?

The most common reefer sizes are 20-foot reefer and 40-foot high-cube reefer. Some carriers and equipment pools also offer 45-foot high-cube reefers, but availability is more limited and the exact spec varies more by fleet.

What temperature range can a reefer container maintain?

Modern marine reefers commonly work in a range around -35 C to +35 C, subject to equipment model, ambient conditions, and commodity requirements. Frozen, chilled, and controlled-atmosphere programs use different operating profiles inside that range.

How much does a reefer container cost?

There is no single global reefer price. Costs depend on lane, season, commodity, inland distance, equipment availability, PTI, power charges, and whether a genset is needed. In most markets, reefer freight carries a clear premium over dry freight.

What is a pre-trip inspection?

PTI is the inspection and functional test performed before a reefer is released for cargo. It checks that the machinery, controls, sensors, alarms, and basic operating condition are suitable for the trip.

How is a reefer container powered during transit?

At terminals and depots, a reefer is usually plugged into shore power. On the vessel, it runs from the ship reefer socket. On inland truck or rail legs, it may depend on a clip-on or undermount genset until the next fixed plug point is available.

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

A dry container is a weatherproof box. A reefer is a weatherproof box plus insulation, machinery, sensors, and operating controls. The reefer protects cargo quality, but it also reduces usable interior space and requires stricter handling throughout the trip.

Need better visibility into reefer milestones, handoffs, and exception risk? Start with Terminal49's Container Tracking API so your team can react faster when temperature-sensitive shipments move off plan.