Ordinary commercial freezers hold around −18 to −25 °C. Ultra-low freezers go much further, using heavier insulation, more powerful or multi-stage refrigeration systems and tighter seals. In food service, temperatures around −40 to −60 °C are used for sashimi-grade fish, premium seafood and some specialist products where colour and texture must be preserved. In labs and hospitals, ULT freezers commonly run around −80 °C for biological samples and reagents.
Running this cold changes how the unit must be treated. It needs space to reject heat, stable power, and time to pull down to temperature. Frost builds quickly in humid air if the lid or door is left open, and staff need insulated gloves to handle stock. Alarms and temperature logging are standard because the contents are often valuable.
A seafood exporter's processing unit in Kochi might keep high-grade tuna loins in an ultra-low chest freezer at around −60 °C, preserving the red colour that buyers expect. A research lab in Pune would use a −80 °C upright for samples.