This benchmark comes from North Dakota State University Extension. It is a planning point, not a guarantee. Freezer design, fullness, room temperature and how often the door opens affect the result.
Before buying anything, keep the door closed
A closed full freezer can hold a safe temperature longer than an open or partly empty one. Check the outage estimate without repeatedly opening the door. Note when power failed and whether the food was still hard-frozen when last checked.
Give the supplier a complete picture
- Freezer capacity in cubic feet
- Chest or upright design
- Full, half full or lightly loaded
- Time already without power
- Best estimate for restoration
- Whether you can consolidate food into a smaller cooler
A full 18-cubic-foot freezer and a half-empty upright should not receive the same recommendation. Extension guidance notes that an upright freezer may need more dry ice because it must be distributed across shelves. If little food remains, moving it to a smaller insulated cooler can be more efficient.
Use the benchmark carefully
| Situation | What changes | Practical response |
|---|---|---|
| Full chest freezer | Dense frozen contents help retain cold | Use the 18-cu.-ft./50-lb benchmark as a call starting point |
| Upright freezer | Cold escapes readily when opened and shelves divide the load | Ask how to divide dry ice among shelves; expect that more may be needed |
| Partly empty freezer | More open air space must be cooled | Consolidate into a smaller freezer or insulated cooler if practical |
| Uncertain restoration time | The holding window may extend beyond the first order | Ask about reserve stock, pickup hours and a second-day plan |
Handle and place it safely
Wear insulated gloves or use tongs. Dry ice is about −109°F (−78.5°C) and can injure bare skin. Follow the supplier’s placement directions for your freezer. Do not put it in an airtight container, and do not remain in an enclosed room where carbon dioxide can build up.
Transport the order in a vented insulated container with outside air moving through the vehicle. CDC workplace guidance recommends the trunk or truck bed when possible and open windows for fresh-air circulation. Never leave dry ice in a parked passenger vehicle.
Food safety still depends on temperature
Dry ice does not make already-thawed food safe again. If food has warmed or you do not know how long it was above a safe temperature, use current food-safety guidance rather than appearance or smell. When in doubt, discard it.