Reefer Capacity Calculator | ContainerMetric
Calculate box capacity for 20ft and 40ft refrigerated containers at target temperature.
Estimating Refrigerated Container Capacity
A refrigerated container (reefer) carries less cargo than a dry box of the same nominal size because the integrated cooling unit and insulated walls eat into the internal envelope. This tool uses ISO 1496-2 nominal reefer dimensions: a 20ft reefer of about 5.44 × 2.29 × 2.27 m, a 40ft reefer of 11.58 × 2.29 × 2.27 m, and a 40ft High Cube reefer of 11.58 × 2.29 × 2.52 m. From those it computes the gross internal volume, then a realistic usable volume.
Usable volume applies a 15% stowage factor (0.85 multiplier) to the gross. That deduction accounts for the rear evaporator and air-return channel plus the ridged T-bar floor, which must stay clear so chilled air can circulate around the cargo. For the 20ft reefer the gross internal volume is roughly 28.3 CBM, leaving about 24 CBM usable once the stowage factor is applied.
Box capacity is then found by testing all six orientations of your carton in an axis-aligned grid and keeping the best fit. The calculator also checks your setpoint against the unit's operating range of −30 °C to +30 °C and flags whether a temperature like −18 °C for frozen goods or +2 °C for chilled produce is within range. Treat the box count as an upper bound, since mixed orientations and packing gaps reduce it in practice.
FAQ
Why does a reefer hold less than a dry container?
The refrigeration unit, thicker insulated walls, the rear air-return channel, and the T-bar floor reduce both the internal dimensions and the usable volume. This tool applies a 15% stowage deduction to reflect that.
What temperature range does the calculator allow?
It checks setpoints against a −30 °C to +30 °C operating range. Frozen cargo typically runs near −18 °C and chilled produce near 0 to +4 °C; both fall within range and the tool flags anything outside it.
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Related Topics
- reefer container calculator
- refrigerated container capacity
- cold chain logistics